feat(api): handle BadRequestException as HTTP 400 and add EmailAccountController

- ExceptionHandlingMiddleware: map BadRequestException to 400 Bad Request response
- Add EmailAccountController: GET /email-accounts (with optional Id/Username filter),
  POST/PUT/DELETE via EmailAccountModificationCommand for full CRUD over email accounts

DigitalData.MessagingService.sln

@@ -37,8 +37,6 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DigitalData.MessagingServic
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DigitalData.MessagingService.Client", "src\presentation\DigitalData.MessagingService.Client\DigitalData.MessagingService.Client.csproj", "{770E96B0-C3C9-A9A3-4F98-F7A0295D1599}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DigitalData.MessagingService.Abstraction", "src\core\DigitalData.MessagingService.Abstraction\DigitalData.MessagingService.Abstraction.csproj", "{6D5E14FC-E4E1-32E3-4F3F-19DE96233128}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -77,10 +75,6 @@ Global
 		{770E96B0-C3C9-A9A3-4F98-F7A0295D1599}.Debug|Any CPU.Build.0 = Release|Any CPU
 		{770E96B0-C3C9-A9A3-4F98-F7A0295D1599}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{770E96B0-C3C9-A9A3-4F98-F7A0295D1599}.Release|Any CPU.Build.0 = Release|Any CPU
-		{6D5E14FC-E4E1-32E3-4F3F-19DE96233128}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{6D5E14FC-E4E1-32E3-4F3F-19DE96233128}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{6D5E14FC-E4E1-32E3-4F3F-19DE96233128}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{6D5E14FC-E4E1-32E3-4F3F-19DE96233128}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -97,7 +91,6 @@ Global
 		{8BF22107-3CB9-C326-B94B-C40C99DA9B68} = {B52B4CEE-1C67-424B-8659-370FEA7EAF2A}
 		{8DBBAA7C-C4D3-4ADD-8372-B0D6260C8FFC} = {71BEA4D0-7835-4A8C-B11E-1088E0801DCE}
 		{770E96B0-C3C9-A9A3-4F98-F7A0295D1599} = {B52B4CEE-1C67-424B-8659-370FEA7EAF2A}
-		{6D5E14FC-E4E1-32E3-4F3F-19DE96233128} = {DD9D4A3A-AB55-456E-80D3-54A2D4025E64}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {90E29FDC-F6C6-414F-94BF-25DF61D18060}

src/core/DigitalData.MessagingService.Abstraction/DigitalData.MessagingService.Abstraction.csproj

@@ -1,10 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-	<TargetFrameworks>net462;net480;net8.0</TargetFrameworks>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-    <LangVersion>latest</LangVersion>
-  </PropertyGroup>
-
-</Project>

src/core/DigitalData.MessagingService.Application/Common/Dto/EmailAccounts/EmailAccountDto.cs

@@ -0,0 +1,46 @@
+namespace DigitalData.MessagingService.Application.Common.Dto.EmailAccounts;
+
+/// <summary>
+/// DTO for a single email account configuration.
+/// </summary>
+public record EmailAccountDto
+{
+    /// <summary>
+    /// Logical name to identify this account (e.g. "default", "support").
+    /// </summary>
+    public int Id { get; set; }
+
+#if NET
+    public required string Username { get; set; }
+#else
+    public string Username { get; set; } = null!;
+#endif
+
+#if NET
+    public required string SmtpServer { get; set; }
+#else
+    public string SmtpServer { get; set; } = null!;
+#endif
+
+    public int SmtpPort { get; set; }
+
+    public bool SmtpUseSsl { get; set; }
+
+    public bool UseOAuth2 { get; set; }
+
+    /// <summary>
+    /// IMAP server hostname (e.g. "imap.example.com").
+    /// Leave empty when this account is send-only.
+    /// </summary>
+    public string? ImapServer { get; set; }
+
+    /// <summary>
+    /// IMAP server port (993 for SSL, 143 for plain/STARTTLS).
+    /// </summary>
+    public int ImapPort { get; set; } = 993;
+
+    /// <summary>
+    /// Use SSL/TLS when connecting to the IMAP server.
+    /// </summary>
+    public bool ImapUseSsl { get; set; } = true;
+}

src/core/DigitalData.MessagingService.Application/Common/Dto/EmailAccounts/EmailAccountModificationDto.cs

@@ -1,15 +1,10 @@
-namespace DigitalData.MessagingService.Abstraction;
+namespace DigitalData.MessagingService.Application.Common.Dto.EmailAccounts;
 
 /// <summary>
 /// DTO for a single email account configuration.
 /// </summary>
-public class EmailAccountDto
+public record EmailAccountModificationDto
 {
-    /// <summary>
-    /// Logical name to identify this account (e.g. "default", "support").
-    /// </summary>
-    public int Id { get; set; }
-
 #if NET
     public required string Username { get; set; }
 #else
@@ -22,8 +17,6 @@ public class EmailAccountDto
     public string Password { get; set; } = null!;
 #endif
 
-    public bool PasswordEncrypted { get; set; } = false;
-
 #if NET
     public required string SmtpServer { get; set; }
 #else
@@ -35,4 +28,20 @@ public class EmailAccountDto
     public bool SmtpUseSsl { get; set; }
 
     public bool UseOAuth2 { get; set; }
+
+    /// <summary>
+    /// IMAP server hostname (e.g. "imap.example.com").
+    /// Leave empty when this account is send-only.
+    /// </summary>
+    public string? ImapServer { get; set; }
+
+    /// <summary>
+    /// IMAP server port (993 for SSL, 143 for plain/STARTTLS).
+    /// </summary>
+    public int ImapPort { get; set; } = 993;
+
+    /// <summary>
+    /// Use SSL/TLS when connecting to the IMAP server.
+    /// </summary>
+    public bool ImapUseSsl { get; set; } = true;
 }

src/core/DigitalData.MessagingService.Application/Common/Dto/EmailAttachmentDto.cs

@@ -1,9 +1,9 @@
-namespace DigitalData.MessagingService.Abstraction;
+namespace DigitalData.MessagingService.Application.Common.Dto;
 
 /// <summary>
 /// Represents a single email attachment.
 /// </summary>
-public sealed class EmailAttachmentContext
+public sealed class EmailAttachmentDto
 {
     /// <summary>
     /// Display name of the attachment (e.g. "invoice.pdf").

src/core/DigitalData.MessagingService.Application/Common/Dto/EmailContext.cs

@@ -1,11 +1,13 @@
-namespace DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Domain.Entities;
+
+namespace DigitalData.MessagingService.Application.Common.Dto;
 
 public record EmailContext
 {
 #if NETFRAMEWORK
-    public EmailAccountDto Sender { get; set; } = null!;
+    public EmailAccount Sender { get; set; } = null!;
 #else
-    public required EmailAccountDto Sender { get; init; }
+    public required EmailAccount Sender { get; init; }
 #endif
 
     /// <summary>
@@ -48,8 +50,8 @@ public record EmailContext
 
     /// <summary>
     /// Optional list of attachments to include with the email.
-    /// Each entry may carry its content as a byte array (<see cref="EmailAttachmentContext.Content"/>)
-    /// or reference a file on disk via <see cref="EmailAttachmentContext.FilePath"/>.
+    /// Each entry may carry its content as a byte array (<see cref="EmailAttachmentDto.Content"/>)
+    /// or reference a file on disk via <see cref="EmailAttachmentDto.FilePath"/>.
     /// </summary>
-    public IEnumerable<EmailAttachmentContext> Attachments { get; set; } = [];
+    public IEnumerable<EmailAttachmentDto> Attachments { get; set; } = [];
 }

src/core/DigitalData.MessagingService.Application/Common/Dto/MailSearch/DateFilter.cs

@@ -0,0 +1,15 @@
+#if NET
+namespace DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+
+/// <summary>
+/// Constrains the search to messages within an arrival-date range.
+/// </summary>
+/// <remarks>
+/// At least one of <see cref="After"/> or <see cref="Before"/> must be provided.
+/// When both are set <see cref="After"/> must be earlier than <see cref="Before"/>.
+/// Both bounds are <b>inclusive</b>.
+/// </remarks>
+/// <param name="After">Earliest date to include (inclusive). Maps to IMAP <c>SINCE</c>.</param>
+/// <param name="Before">Latest date to include (inclusive). Maps to IMAP <c>BEFORE</c> (next day is used internally).</param>
+public record DateFilter(DateTime? After = null, DateTime? Before = null);
+#endif

src/core/DigitalData.MessagingService.Application/Common/Dto/MailSearch/MailSearchFilter.cs

@@ -0,0 +1,80 @@
+#if NET
+namespace DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+
+/// <summary>
+/// Describes all criteria and options used when searching an IMAP mailbox.
+/// </summary>
+/// <remarks>
+/// All text-match properties are <b>case-insensitive</b> substring searches performed server-side via IMAP SEARCH.
+/// Combine multiple criteria freely; an implicit AND is applied across all non-null fields.
+/// </remarks>
+public record MailSearchFilter
+{
+    /// <summary>
+    /// Mailbox folder to search. Defaults to <c>"INBOX"</c>.
+    /// </summary>
+    public string Folder { get; init; } = "INBOX";
+
+    /// <summary>
+    /// When <see langword="true"/>, only unread (UNSEEN) messages are returned.
+    /// </summary>
+    public bool UnseenOnly { get; init; } = false;
+
+    /// <summary>
+    /// When <see langword="true"/>, attachment data is included in the results; otherwise attachments are omitted.
+    /// Defaults to <see langword="false"/>.
+    /// </summary>
+    public bool WithAttachments { get; init; } = false;
+
+    /// <summary>
+    /// Maximum number of messages to retrieve. <c>0</c> means unlimited.
+    /// Applied after sorting; defaults to <c>50</c>.
+    /// </summary>
+    public int? MaxCount { get; init; } = null;
+
+    /// <summary>
+    /// Controls the order of the returned messages. Defaults to <see cref="MailSortOrder.NewestFirst"/>.
+    /// </summary>
+    public MailSortOrder SortOrder { get; init; } = MailSortOrder.NewestFirst;
+
+    // ── Text filters ───────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Case-insensitive substring the message subject must contain.
+    /// Maps to IMAP <c>SUBJECT</c>.
+    /// </summary>
+    public string? SubjectContains { get; init; } = null;
+
+    /// <summary>
+    /// Case-insensitive substring that must appear in the <c>From</c> header.
+    /// Maps to IMAP <c>FROM</c>.
+    /// </summary>
+    public string? SenderContains { get; init; } = null;
+
+    /// <summary>
+    /// Case-insensitive substring that must appear in <c>To</c> or <c>Cc</c>.
+    /// Maps to IMAP <c>TO</c>.
+    /// </summary>
+    public string? RecipientContains { get; init; } = null;
+
+    /// <summary>
+    /// Case-insensitive substring that must appear anywhere in the message body (text or HTML part).
+    /// Maps to IMAP <c>BODY</c>.
+    /// </summary>
+    public string? BodyContains { get; init; } = null;
+
+    // ── Structured filters ─────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Constrains results to a specific UID or a UID range.
+    /// See <see cref="UidFilter"/> for mutual-exclusion rules between its fields.
+    /// </summary>
+    public UidFilter? Uid { get; init; } = null;
+
+    /// <summary>
+    /// Constrains results to messages received within a date range.
+    /// See <see cref="DateFilter"/> for rules between its fields.
+    /// </summary>
+    public DateFilter? Date { get; init; } = null;
+}
+#endif

src/core/DigitalData.MessagingService.Application/Common/Dto/MailSearch/MailSortOrder.cs

@@ -0,0 +1,17 @@
+namespace DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+
+/// <summary>
+/// Controls the order in which fetched messages are returned.
+/// </summary>
+public enum MailSortOrder
+{
+    /// <summary>
+    /// Newest messages first (default).
+    /// </summary>
+    NewestFirst,
+
+    /// <summary>
+    /// Oldest messages first.
+    /// </summary>
+    OldestFirst
+}

src/core/DigitalData.MessagingService.Application/Common/Dto/MailSearch/UidFilter.cs

@@ -0,0 +1,16 @@
+#if NET
+namespace DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+
+/// <summary>
+/// Constrains the search to a specific UID or a UID range.
+/// </summary>
+/// <remarks>
+/// Use <see cref="Absolute"/> for an exact single-message lookup.
+/// Use <see cref="Min"/> and/or <see cref="Max"/> for an open or closed range.
+/// Mixing <see cref="Absolute"/> with <see cref="Min"/> or <see cref="Max"/> is not allowed.
+/// </remarks>
+/// <param name="Min">Lower bound of the UID range (inclusive). Ignored when <see cref="Absolute"/> is set.</param>
+/// <param name="Max">Upper bound of the UID range (inclusive). Ignored when <see cref="Absolute"/> is set.</param>
+/// <param name="Absolute">Exact UID to match. When set, <see cref="Min"/> and <see cref="Max"/> must be <see langword="null"/>.</param>
+public record UidFilter(long? Min = null, long? Max = null, long? Absolute = null);
+#endif

src/core/DigitalData.MessagingService.Application/Common/Dto/ReceivedEmailDto.cs

@@ -0,0 +1,97 @@
+namespace DigitalData.MessagingService.Application.Common.Dto;
+
+/// <summary>
+/// Represents an email message received via IMAP.
+/// </summary>
+public sealed record ReceivedEmailDto
+{
+    /// <summary>
+    /// Unique identifier of the message on the IMAP server (UID).
+    /// </summary>
+#if NET
+    public long Uid { get; init; }
+#else
+    public long Uid { get; set; }
+#endif
+
+    /// <summary>
+    /// Sender address (From header).
+    /// </summary>
+#if NET
+    public string From { get; init; } = string.Empty;
+#else
+    public string From { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// Recipient addresses (To header).
+    /// </summary>
+#if NET
+    public IEnumerable<string> To { get; init; } = [];
+#else
+    public IEnumerable<string> To { get; set; } = [];
+#endif
+
+    /// <summary>
+    /// CC addresses.
+    /// </summary>
+#if NET
+    public IEnumerable<string> Cc { get; init; } = [];
+#else
+    public IEnumerable<string> Cc { get; set; } = [];
+#endif
+
+    /// <summary>
+    /// Email subject.
+    /// </summary>
+#if NET
+    public string Subject { get; init; } = string.Empty;
+#else
+    public string Subject { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// Plain-text body (may be empty when only HTML is present).
+    /// </summary>
+#if NET
+    public string TextBody { get; init; } = string.Empty;
+#else
+    public string TextBody { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// HTML body (may be empty when only plain-text is present).
+    /// </summary>
+#if NET
+    public string HtmlBody { get; init; } = string.Empty;
+#else
+    public string HtmlBody { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// Date/time the message was sent (Date header).
+    /// </summary>
+#if NET
+    public DateTime Date { get; init; }
+#else
+    public DateTime Date { get; set; }
+#endif
+
+    /// <summary>
+    /// Attachments included with this message.
+    /// </summary>
+#if NET
+    public IEnumerable<EmailAttachmentDto> Attachments { get; init; } = [];
+#else
+    public IEnumerable<EmailAttachmentDto> Attachments { get; set; } = [];
+#endif
+
+    /// <summary>
+    /// Whether the message has been marked as seen/read on the server.
+    /// </summary>
+#if NET
+    public bool IsSeen { get; init; }
+#else
+    public bool IsSeen { get; set; }
+#endif
+}

src/core/DigitalData.MessagingService.Application/Common/Dto/SendingEmailCreateDto.cs

@@ -1,4 +1,4 @@
-namespace DigitalData.MessagingService.Abstraction;
+namespace DigitalData.MessagingService.Application.Common.Dto;
 
 public record SendingEmailCreateDto
 {

src/core/DigitalData.MessagingService.Application/Common/Dto/SendingEmailEvent.cs

@@ -1,4 +1,4 @@
-namespace DigitalData.MessagingService.Abstraction;
+namespace DigitalData.MessagingService.Application.Common.Dto;
 
 public record SendingEmailEvent
 {

src/core/DigitalData.MessagingService.Application/Common/Interfaces/IEmailService.cs

@@ -1,4 +1,4 @@
-using DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Application.Common.Dto;
 
 namespace DigitalData.MessagingService.Application.Common.Interfaces;
 

src/core/DigitalData.MessagingService.Application/Common/Interfaces/IImapEmailService.cs

@@ -0,0 +1,36 @@
+#if NET
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+using DigitalData.MessagingService.Domain.Entities;
+
+namespace DigitalData.MessagingService.Application.Common.Interfaces;
+
+/// <summary>
+/// Service interface for reading emails via IMAP.
+/// </summary>
+public interface IImapEmailService
+{
+    /// <summary>
+    /// Fetches emails from the specified mailbox folder.
+    /// </summary>
+    /// <param name="account">Account whose IMAP settings will be used.</param>
+    /// <param name="filter">Filter to apply when fetching emails.</param>
+    /// When <see langword="true"/> (default), fetched messages are marked as <c>\Seen</c> on the server.
+    /// Set to <see langword="false"/> for a non-destructive read (uses <c>BODY.PEEK</c> internally).
+    /// </param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    Task<IEnumerable<ReceivedEmailDto>> FetchEmailsAsync(
+        EmailAccount account,
+        MailSearchFilter filter,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Marks a message as seen (read) on the server.
+    /// </summary>
+    Task MarkAsSeenAsync(
+        EmailAccount account,
+        long uid,
+        string folder = "INBOX",
+        CancellationToken cancellationToken = default);
+}
+#endif

src/core/DigitalData.MessagingService.Application/Common/Interfaces/ISendingEmailPublisher.cs

@@ -1,4 +1,6 @@
-namespace DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Application.Common.Dto;
+
+namespace DigitalData.MessagingService.Application.Common.Interfaces;
 
 /// <summary>
 /// Email queue interface for outgoing emails.
@@ -8,4 +10,4 @@ public interface ISendingEmailPublisher
     Task EnqueueAsync(SendingEmailEvent sendingEmailEvent, CancellationToken cancellationToken = default);
 
     Task<int> GetQueueDepthAsync(CancellationToken cancellationToken = default);
-}
+}

src/core/DigitalData.MessagingService.Application/Common/Interfaces/Repositories/IRepository.cs

@@ -11,6 +11,8 @@ public interface IRepository<TEntity> where TEntity : class
     // CREATE
     Task<TEntity> CreateAsync<TDto>(TDto dto, CancellationToken cancellationToken = default);
 
+    Task<IEnumerable<TEntity>> CreateAsync<TDto>(IEnumerable<TDto> dtos, CancellationToken cancellationToken = default);
+
     // READ
     Task<TEntity?> GetByIdAsync(int id, CancellationToken cancellationToken = default);
     Task<IEnumerable<TEntity>> GetAllAsync(CancellationToken cancellationToken = default);
@@ -20,6 +22,11 @@ public interface IRepository<TEntity> where TEntity : class
     Task<int> CountAsync(Expression<Func<TEntity, bool>>? predicate = null, CancellationToken cancellationToken = default);
     Task<bool> AnyAsync(Expression<Func<TEntity, bool>> predicate, CancellationToken cancellationToken = default);
 
+    // UPSERT
+    Task<(TEntity Entity, bool Created)> UpsertAsync<TDto>(Expression<Func<TEntity, bool>> predicate, TDto dto, CancellationToken cancellationToken = default);
+    
+    Task<(TEntity Entity, bool Created)> UpsertSingleAsync<TDto>(Expression<Func<TEntity, bool>> predicate, TDto dto, CancellationToken cancellationToken = default);
+
     // UPDATE
     Task UpdateSingleAsync<TDto>(Expression<Func<TEntity, bool>> predicate, TDto dto, CancellationToken cancellationToken = default);
     Task<int> UpdateAsync<TDto>(Expression<Func<TEntity, bool>> predicate, TDto dto, CancellationToken cancellationToken = default);

src/core/DigitalData.MessagingService.Application/Common/Mappings/EmailMappingProfile.cs

@@ -1,6 +1,9 @@
+#if NET
 using AutoMapper;
 using DigitalData.MessagingService.Application.EmailSending.Commands;
-using DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Domain.Entities;
+using DigitalData.MessagingService.Application.Common.Dto.EmailAccounts;
 
 namespace DigitalData.MessagingService.Application.Common.Mappings;
 
@@ -11,10 +14,15 @@ public class EmailMappingProfile : Profile
 {
     public EmailMappingProfile()
     {
-        // SendEmailCommand -> Email
+        // PublishEmailCommand -> Email
         // Sender is resolved via MediatR in the handler and set separately after mapping.
-        CreateMap<SendEmailCommand, EmailContext>()
+        CreateMap<PublishEmailCommand, EmailContext>()
             .ForMember(dest => dest.Sender, opt => opt.Ignore())
             .ForMember(dest => dest.Attachments, opt => opt.MapFrom(src => src.Attachments));
+
+        // EmailAccountDto -> EmailAccount
+        CreateMap<EmailAccount, EmailAccountDto>();
+        CreateMap<EmailAccountModificationDto, EmailAccount>();
     }
 }
+#endif

src/core/DigitalData.MessagingService.Application/Common/Options/EmailAccountsOptions.cs

@@ -1,9 +1,13 @@
-using DigitalData.MessagingService.Abstraction;
+#if NET
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Dto.EmailAccounts;
+using DigitalData.MessagingService.Application.EmailAccounts.Commands;
+using DigitalData.MessagingService.Domain.Entities;
 
 namespace DigitalData.MessagingService.Application.Common.Options;
 
 /// <summary>
-/// Wrapper options class that holds a list of <see cref="EmailAccountDto"/> entries
+/// Wrapper options class that holds a list of <see cref="Dto.EmailAccount"/> entries
 /// bound from the <c>EmailAccounts</c> configuration section.
 /// </summary>
 public class EmailAccountsOptions
@@ -13,5 +17,12 @@ public class EmailAccountsOptions
     /// <summary>
     /// The list of configured email accounts.
     /// </summary>
-    public required IEnumerable<EmailAccountDto> Accounts { get; init; } = [];
+    public required IEnumerable<EmailAccountModificationDto> Accounts { get; init; } = [];
+
+    /// <summary>
+    /// How often the IMAP sync worker polls for new emails, in seconds.
+    /// Defaults to 300 seconds (5 minutes).
+    /// </summary>
+    public int SyncIntervalSeconds { get; init; } = 300;
 }
+#endif

src/core/DigitalData.MessagingService.Application/Common/ValueObjects/Modification.cs

@@ -0,0 +1,6 @@
+namespace DigitalData.MessagingService.Application.Common.ValueObjects;
+
+public enum Modification
+{
+    Upsert
+}

src/core/DigitalData.MessagingService.Application/DependencyInjection.cs

@@ -1,8 +1,8 @@
+#if NET
 using DigitalData.MessagingService.Application.Common.Options;
 using FluentValidation;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Options;
 using System.Reflection;
 
 namespace DigitalData.MessagingService.Application;
@@ -43,3 +43,4 @@ public static class DependencyInjection
         return services;
     }
 }
+#endif

src/core/DigitalData.MessagingService.Application/DigitalData.MessagingService.Application.csproj

@@ -1,17 +1,17 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
+	  <TargetFrameworks>net462;net480;net8.0</TargetFrameworks>
+	  <ImplicitUsings>enable</ImplicitUsings>
+	  <Nullable>enable</Nullable>
+	  <LangVersion>latest</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\DigitalData.MessagingService.Domain\DigitalData.MessagingService.Domain.csproj" />
-    <ProjectReference Include="..\DigitalData.MessagingService.Abstraction\DigitalData.MessagingService.Abstraction.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetFramework)' == 'net8.0'">
     <PackageReference Include="AutoMapper" Version="16.2.0" />
     <PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="12.1.1" />
     <PackageReference Include="MediatR" Version="14.2.0" />

src/core/DigitalData.MessagingService.Application/EmailAccount/Queries/GetSenderQuery.cs

@@ -1,39 +0,0 @@
-using DigitalData.MessagingService.Application.Common.Options;
-using DigitalData.MessagingService.Abstraction;
-using MediatR;
-using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Options;
-
-namespace DigitalData.MessagingService.Application.EmailAccount.Queries;
-
-public record GetSenderQuery : IRequest<EmailAccountDto?>
-{
-    public int? Id { get; init; }
-
-    public string? Username { get; init; }
-}
-
-/// <summary>
-/// 
-/// </summary>
-/// <param name="Options"></param>
-/// <param name="Logger"></param>
-public class GetSenderQueryHandler(IOptions<EmailAccountsOptions> Options, ILogger<GetSenderQueryHandler> Logger) : IRequestHandler<GetSenderQuery, EmailAccountDto?>
-{
-    public Task<EmailAccountDto?> Handle(GetSenderQuery request, CancellationToken cancellationToken)
-    {
-        var accounts = request.Id is not null 
-            ? Options.Value.Accounts.Where(a => a.Id == request.Id)
-            : Options.Value.Accounts.Where(a => a.Username == request.Username);
-
-        if(accounts.Count() > 1)
-        {
-            Logger.LogWarning(
-                "Multiple email accounts found for the given criteria ({Criteria}). Returning the first one.",
-                request.Id is not null ? $"Id: {request.Id}" : $"Username: {request.Username}"
-            );
-        }
-
-        return Task.FromResult(accounts.FirstOrDefault());
-    }
-}

src/core/DigitalData.MessagingService.Application/EmailAccount/Validators/GetSenderQueryValidator.cs

@@ -1,27 +0,0 @@
-using DigitalData.MessagingService.Application.EmailAccount.Queries;
-using FluentValidation;
-
-namespace DigitalData.MessagingService.Application.EmailAccount.Validators;
-
-/// <summary>
-/// Validator for <see cref="GetSenderQuery"/>.
-/// Either <see cref="GetSenderQuery.Id"/> or <see cref="GetSenderQuery.Username"/> must be provided, but not both.
-/// </summary>
-public class GetSenderQueryValidator : AbstractValidator<GetSenderQuery>
-{
-    public GetSenderQueryValidator()
-    {
-        RuleFor(x => x)
-            .Must(x => (x.Id is not null) ^ (x.Username is not null))
-            .WithMessage("Either Id or Username must be provided, but not both.");
-
-        When(x => x.Username is not null, () =>
-        {
-            RuleFor(x => x.Username)
-                .NotEmpty()
-                .WithMessage("Username must not be empty.")
-                .MaximumLength(200)
-                .WithMessage("Username must not exceed 200 characters.");
-        });
-    }
-}

src/core/DigitalData.MessagingService.Application/EmailAccounts/Commands/EmailAccountModificationCommand.cs

@@ -0,0 +1,36 @@
+#if NET
+using DigitalData.MessagingService.Application.Common.Dto.EmailAccounts;
+using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
+using DigitalData.MessagingService.Application.Common.ValueObjects;
+using DigitalData.MessagingService.Domain.Entities;
+using MediatR;
+using System.Security.Principal;
+
+namespace DigitalData.MessagingService.Application.EmailAccounts.Commands;
+
+/// <summary>
+/// DTO for a single email account configuration.
+/// </summary>
+public record EmailAccountModificationCommand : IRequest<(EmailAccount, bool)>
+{
+    public required EmailAccountModificationDto ModifiedAccount { get; init; }
+
+    public required Modification Modification { get; init; }
+}
+
+/// <summary>
+/// 
+/// </summary>
+/// <param name="Repo"></param>
+public class EmailAccountModificationCommandHandler(IRepository<EmailAccount> Repo) : IRequestHandler<EmailAccountModificationCommand, (EmailAccount, bool)>
+{
+    public async Task<(EmailAccount, bool)> Handle(EmailAccountModificationCommand request, CancellationToken cancellationToken)
+    {
+        return request.Modification switch
+        {
+            Modification.Upsert => await Repo.UpsertAsync(a => a.Username == request.ModifiedAccount.Username, request.ModifiedAccount, cancellationToken),
+            _ => throw new NotSupportedException($"Modification type '{request.Modification}' is not supported in email account modification."),
+        };
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailAccounts/Queries/GetEmailAccountQuery.cs

@@ -0,0 +1,37 @@
+#if NET
+using MediatR;
+using DigitalData.MessagingService.Domain.Entities;
+using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
+using AutoMapper;
+using DigitalData.MessagingService.Domain.Exceptions;
+using DigitalData.MessagingService.Application.Common.Dto.EmailAccounts;
+
+namespace DigitalData.MessagingService.Application.EmailAccounts.Queries;
+
+public record GetEmailAccountQuery : IRequest<IEnumerable<EmailAccountDto>>
+{
+    public int? Id { get; init; }
+
+    public string? Username { get; init; }
+}
+
+/// <summary>
+/// Handles queries for retrieving email accounts.
+/// </summary>
+/// <param name="Repo"></param>
+/// <param name="Mapper"></param>
+public class GetEmailAccountQueryHandler(IRepository<EmailAccount> Repo, IMapper Mapper) : IRequestHandler<GetEmailAccountQuery, IEnumerable<EmailAccountDto>>
+{
+    public async Task<IEnumerable<EmailAccountDto>> Handle(GetEmailAccountQuery request, CancellationToken cancellationToken)
+    {
+        var accounts = request.Id is null && request.Username is null 
+            ? await Repo.GetAllAsync(cancellationToken) 
+            : await Repo.FindAsync(request.Id is int id ? x => x.Id == id : x => x.Username == request.Username, cancellationToken: cancellationToken);
+
+        if (accounts.Any())
+            return Mapper.Map<IEnumerable<EmailAccountDto>>(accounts);
+        else
+            throw new NotFoundException($"No email account found for the given criteria ({(request.Id is not null ? $"Id: {request.Id}" : $"Username: {request.Username}")}).");
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailAccounts/Validators/GetSenderQueryValidator.cs

@@ -0,0 +1,25 @@
+#if NET
+using DigitalData.MessagingService.Application.EmailAccounts.Queries;
+using FluentValidation;
+
+namespace DigitalData.MessagingService.Application.EmailAccounts.Validators;
+
+/// <summary>
+/// Validator for <see cref="GetEmailAccountQuery"/>.
+/// Either <see cref="GetEmailAccountQuery.Id"/> or <see cref="GetEmailAccountQuery.Username"/> must be provided, but not both.
+/// </summary>
+public class GetSenderQueryValidator : AbstractValidator<GetEmailAccountQuery>
+{
+    public GetSenderQueryValidator()
+    {
+        When(x => x.Username is not null, () =>
+        {
+            RuleFor(x => x.Username)
+                .NotEmpty()
+                .WithMessage("Username must not be empty.")
+                .MaximumLength(200)
+                .WithMessage("Username must not exceed 200 characters.");
+        });
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailReceiving/Commands/MarkEmailAsSeenCommand.cs

@@ -0,0 +1,48 @@
+#if NET
+using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
+using DigitalData.MessagingService.Application.EmailAccounts.Queries;
+using DigitalData.MessagingService.Domain.Entities;
+using DigitalData.MessagingService.Domain.Exceptions;
+using MediatR;
+using Microsoft.Extensions.Logging;
+
+namespace DigitalData.MessagingService.Application.EmailReceiving.Commands;
+
+/// <summary>
+/// Command to mark a single IMAP message as seen (read).
+/// </summary>
+public record MarkEmailAsSeenCommand : IRequest
+{
+    public required GetEmailAccountQuery Account { get; init; }
+
+    /// <summary>
+    /// UID of the message to mark as seen.
+    /// </summary>
+    public required long Uid { get; init; }
+
+    /// <summary>
+    /// Mailbox folder the message resides in (default: "INBOX").
+    /// </summary>
+    public string Folder { get; init; } = "INBOX";
+}
+
+public class MarkEmailAsSeenCommandHandler(IImapEmailService ImapService, ILogger<MarkEmailAsSeenCommandHandler> Logger, IRepository<EmailAccount> Repo) : IRequestHandler<MarkEmailAsSeenCommand>
+{
+    public async Task Handle(MarkEmailAsSeenCommand request, CancellationToken cancellationToken)
+    {
+        var accounts = await Repo.FindAsync(request.Account.Id is int id ? x => x.Id == id : x => x.Username == request.Account.Username, cancellationToken: cancellationToken);
+
+        if (accounts.Count() > 1)
+            Logger.LogWarning("Multiple email accounts found for the given criteria ({Criteria}). Returning the first one.", request.Account.Id is not null ? $"Id: {request.Account.Id}" : $"Username: {request.Account.Username}");
+
+        var account = accounts.FirstOrDefault()
+            ?? throw new NotFoundException($"No email account found for the given criteria (Id: {request.Account.Id}, Username: {request.Account.Username}).");
+
+        if (string.IsNullOrWhiteSpace(account.ImapServer))
+            throw new BadRequestException($"IMAP is not configured for account '{account.Username}' (Id: {account.Id}). Set ImapServer in EmailAccounts configuration.");
+
+        await ImapService.MarkAsSeenAsync(account, request.Uid, request.Folder, cancellationToken);
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailReceiving/Queries/FetchEmailsQuery.cs

@@ -0,0 +1,52 @@
+#if NET
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
+using DigitalData.MessagingService.Application.EmailAccounts.Queries;
+using DigitalData.MessagingService.Domain.Entities;
+using DigitalData.MessagingService.Domain.Exceptions;
+using MediatR;
+using Microsoft.Extensions.Logging;
+
+namespace DigitalData.MessagingService.Application.EmailReceiving.Queries;
+
+/// <summary>
+/// Query to fetch emails from an IMAP mailbox.
+/// </summary>
+public record FetchEmailsQuery : IRequest<IEnumerable<ReceivedEmailDto>>
+{
+    /// <summary>
+    /// Identifies the email account to use.
+    /// </summary>
+    public required GetEmailAccountQuery Account { get; init; }
+
+    /// <summary>
+    /// Mail query used to filter and limit the emails retrieved.
+    /// </summary>
+    public MailSearchFilter Mail { get; init; } = new();
+}
+
+public class FetchEmailsQueryHandler(IImapEmailService ImapService, ILogger<FetchEmailsQueryHandler> Logger, IRepository<EmailAccount> Repo) : IRequestHandler<FetchEmailsQuery, IEnumerable<ReceivedEmailDto>>
+{
+    public async Task<IEnumerable<ReceivedEmailDto>> Handle(FetchEmailsQuery request, CancellationToken cancellationToken)
+    {
+        var accounts = await Repo.FindAsync(request.Account.Id is int id ? x => x.Id == id : x => x.Username == request.Account.Username, cancellationToken: cancellationToken);
+
+        if (accounts.Count() > 1)
+            Logger.LogWarning("Multiple email accounts found for the given criteria ({Criteria}). Returning the first one.", request.Account.Id is not null ? $"Id: {request.Account.Id}" : $"Username: {request.Account.Username}");
+
+        EmailAccount account = accounts.FirstOrDefault()
+            ?? throw new NotFoundException($"No email account found for the given criteria (Id: {request.Account.Id}, Username: {request.Account.Username}).");
+
+        if (string.IsNullOrWhiteSpace(account.ImapServer))
+            throw new BadRequestException(
+                $"IMAP is not configured for account '{account.Username}' (Id: {account.Id}). Set ImapServer in EmailAccounts configuration.");
+
+        return await ImapService.FetchEmailsAsync(
+            account,
+            request.Mail,
+            cancellationToken);
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailReceiving/Validators/DateFilterValidator.cs

@@ -0,0 +1,39 @@
+#if NET
+using DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+using FluentValidation;
+
+namespace DigitalData.MessagingService.Application.EmailReceiving.Validators;
+
+/// <summary>
+/// Validates a <see cref="DateFilter"/> value object.
+/// </summary>
+public class DateFilterValidator : AbstractValidator<DateFilter>
+{
+    public DateFilterValidator()
+    {
+        // At least one field must be provided
+        RuleFor(x => x)
+            .Must(d => d.After is not null || d.Before is not null)
+            .WithName("Date")
+            .WithMessage("DateFilter must specify at least one of: After or Before.");
+
+        // Dates must not be in the future
+        RuleFor(x => x.After)
+            .LessThanOrEqualTo(DateTime.UtcNow)
+            .WithMessage("Date.After must not be in the future.")
+            .When(x => x.After is not null);
+
+        RuleFor(x => x.Before)
+            .LessThanOrEqualTo(DateTime.UtcNow)
+            .WithMessage("Date.Before must not be in the future.")
+            .When(x => x.Before is not null);
+
+        // Range coherence: After must be earlier than Before
+        RuleFor(x => x)
+            .Must(d => d.After!.Value < d.Before!.Value)
+            .WithName("Date.Range")
+            .WithMessage("Date.After must be earlier than Date.Before.")
+            .When(x => x.After is not null && x.Before is not null);
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailReceiving/Validators/FetchEmailsQueryValidator.cs

@@ -0,0 +1,24 @@
+#if NET
+using DigitalData.MessagingService.Application.EmailReceiving.Queries;
+using FluentValidation;
+
+namespace DigitalData.MessagingService.Application.EmailReceiving.Validators;
+
+/// <summary>
+/// Validates a <see cref="FetchEmailsQuery"/> before it is handled by <see cref="FetchEmailsQueryHandler"/>.
+/// </summary>
+public class FetchEmailsQueryValidator : AbstractValidator<FetchEmailsQuery>
+{
+    public FetchEmailsQueryValidator()
+    {
+        RuleFor(x => x.Account)
+            .NotNull()
+            .WithMessage("Account query must not be null.");
+
+        RuleFor(x => x.Mail)
+            .NotNull()
+            .WithMessage("Mail search filter must not be null.")
+            .SetValidator(new MailSearchFilterValidator());
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailReceiving/Validators/MailSearchFilterValidator.cs

@@ -0,0 +1,53 @@
+#if NET
+using DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+using FluentValidation;
+
+namespace DigitalData.MessagingService.Application.EmailReceiving.Validators;
+
+/// <summary>
+/// Validates a <see cref="MailSearchFilter"/> instance before it is dispatched to the IMAP service.
+/// </summary>
+public class MailSearchFilterValidator : AbstractValidator<MailSearchFilter>
+{
+    public MailSearchFilterValidator()
+    {
+        RuleFor(x => x.Folder)
+            .NotEmpty()
+            .WithMessage("Folder must not be empty.")
+            .MaximumLength(255)
+            .WithMessage("Folder name must not exceed 255 characters.");
+
+        RuleFor(x => x.MaxCount)
+            .GreaterThanOrEqualTo(0)
+            .WithMessage("MaxCount must be 0 (unlimited) or a positive number.");
+
+        RuleFor(x => x.SubjectContains)
+            .MaximumLength(500)
+            .WithMessage("SubjectContains must not exceed 500 characters.")
+            .When(x => x.SubjectContains is not null);
+
+        RuleFor(x => x.SenderContains)
+            .MaximumLength(320)
+            .WithMessage("SenderContains must not exceed 320 characters.")
+            .When(x => x.SenderContains is not null);
+
+        RuleFor(x => x.RecipientContains)
+            .MaximumLength(320)
+            .WithMessage("RecipientContains must not exceed 320 characters.")
+            .When(x => x.RecipientContains is not null);
+
+        RuleFor(x => x.BodyContains)
+            .MaximumLength(1000)
+            .WithMessage("BodyContains must not exceed 1000 characters.")
+            .When(x => x.BodyContains is not null);
+
+        RuleFor(x => x.Uid)
+            .SetValidator(new UidFilterValidator()!)
+            .When(x => x.Uid is not null);
+
+        RuleFor(x => x.Date)
+            .SetValidator(new DateFilterValidator()!)
+            .When(x => x.Date is not null);
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailReceiving/Validators/UidFilterValidator.cs

@@ -0,0 +1,50 @@
+#if NET
+using DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+using FluentValidation;
+
+namespace DigitalData.MessagingService.Application.EmailReceiving.Validators;
+
+/// <summary>
+/// Validates a <see cref="UidFilter"/> value object.
+/// </summary>
+public class UidFilterValidator : AbstractValidator<UidFilter>
+{
+    public UidFilterValidator()
+    {
+        // Absolute and range are mutually exclusive
+        RuleFor(x => x)
+            .Must(u => u.Absolute is null || (u.Min is null && u.Max is null))
+            .WithName("Uid.Absolute")
+            .WithMessage("Uid.Absolute cannot be combined with Uid.Min or Uid.Max. Use either an exact UID or a range.");
+
+        // At least one field must be provided
+        RuleFor(x => x)
+            .Must(u => u.Absolute is not null || u.Min is not null || u.Max is not null)
+            .WithName("Uid")
+            .WithMessage("UidFilter must specify at least one of: Absolute, Min, or Max.");
+
+        // All UID values must be positive
+        RuleFor(x => x.Absolute)
+            .GreaterThan(0)
+            .WithMessage("Uid.Absolute must be a positive number.")
+            .When(x => x.Absolute is not null);
+
+        RuleFor(x => x.Min)
+            .GreaterThan(0)
+            .WithMessage("Uid.Min must be a positive number.")
+            .When(x => x.Min is not null);
+
+        RuleFor(x => x.Max)
+            .GreaterThan(0)
+            .WithMessage("Uid.Max must be a positive number.")
+            .When(x => x.Max is not null);
+
+        // Range coherence: Min must be less than or equal to Max
+        RuleFor(x => x)
+            .Must(u => u.Min!.Value <= u.Max!.Value)
+            .WithName("Uid.Range")
+            .WithMessage("Uid.Min must be less than or equal to Uid.Max.")
+            .When(x => x.Min is not null && x.Max is not null);
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailSending/Commands/PublishEmailCommand.cs

@@ -0,0 +1,82 @@
+#if NET
+using AutoMapper;
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
+using DigitalData.MessagingService.Application.EmailAccounts.Queries;
+using DigitalData.MessagingService.Domain.Entities;
+using DigitalData.MessagingService.Domain.Exceptions;
+using MediatR;
+using Microsoft.Extensions.Logging;
+using System.Text.Json.Serialization;
+
+namespace DigitalData.MessagingService.Application.EmailSending.Commands;
+
+/// <summary>
+/// Command to send an email (enqueue to RabbitMQ)
+/// </summary>
+public record PublishEmailCommand : IRequest<Guid>
+{
+    public required GetEmailAccountQuery Sender { get; init; }
+
+    /// <summary>
+    /// Recipient email addresses
+    /// </summary>
+    public required IEnumerable<string> Recipients { get; init; }
+
+    /// <summary>
+    /// Email subject
+    /// </summary>
+    public required string Subject { get; init; }
+
+    /// <summary>
+    /// Email body (HTML or plain text)
+    /// </summary>
+    public required string Body { get; init; }
+
+    /// <summary>
+    /// Is HTML email (default: true)
+    /// </summary>
+    public bool IsHtml { get; init; } = true;
+
+    [JsonIgnore]
+    internal IEnumerable<EmailAttachmentDto> Attachments { get; private init; } = [];
+
+    /// <summary>
+    /// Returns a new command instance with the supplied attachments.
+    /// Called by the controller after resolving uploaded files.
+    /// </summary>
+    public PublishEmailCommand WithAttachments(IEnumerable<EmailAttachmentDto> attachments)
+        => this with { Attachments = attachments };
+}
+
+/// <summary>
+/// Handler for PublishEmailCommand
+/// Resolves the sender account via MediatR, maps to SendingEmailEvent and enqueues to RabbitMQ
+/// </summary>
+public class PublishEmailCommandHandler(IRepository<EmailAccount> Repo, ISendingEmailPublisher Publisher, IMapper Mapper, ILogger<PublishEmailCommandHandler> Logger) : IRequestHandler<PublishEmailCommand, Guid>
+{
+    public async Task<Guid> Handle(PublishEmailCommand request, CancellationToken cancellationToken)
+    {
+        var senderAccounts = await Repo.FindAsync(request.Sender.Id is int id ? x => x.Id == id : x => x.Username == request.Sender.Username, cancellationToken: cancellationToken);
+
+        if (senderAccounts.Count() > 1)
+            Logger.LogWarning("Multiple email accounts found for the given criteria ({Criteria}). Returning the first one.", request.Sender.Id is not null ? $"Id: {request.Sender.Id}" : $"Username: {request.Sender.Username}");
+
+        var senderAccount = senderAccounts.FirstOrDefault()
+            ?? throw new NotFoundException($"No email account found for the given sender criteria (Id: {request.Sender.Id}, Username: {request.Sender.Username}).");
+
+        var email = Mapper.Map<EmailContext>(request) with { Sender = senderAccount };
+
+        // Enqueue to RabbitMQ
+        var sendingEmailEvent = new SendingEmailEvent()
+        {
+            Id = Guid.NewGuid(),
+            Mail = email,
+            QueuedAt = DateTime.Now
+        };
+        await Publisher.EnqueueAsync(sendingEmailEvent, cancellationToken);
+        return sendingEmailEvent.Id;
+    }
+}
+#endif

src/core/DigitalData.MessagingService.Application/EmailSending/Commands/SendEmailCommand.cs

@@ -1,72 +0,0 @@
-using AutoMapper;
-using DigitalData.MessagingService.Application.EmailAccount.Queries;
-using DigitalData.MessagingService.Domain.Exceptions;
-using DigitalData.MessagingService.Abstraction;
-using MediatR;
-using System.Text.Json.Serialization;
-
-namespace DigitalData.MessagingService.Application.EmailSending.Commands;
-
-/// <summary>
-/// Command to send an email (enqueue to RabbitMQ)
-/// </summary>
-public record SendEmailCommand : IRequest<Guid>
-{
-    public required GetSenderQuery Sender { get; init; }
-
-    /// <summary>
-    /// Recipient email addresses
-    /// </summary>
-    public required IEnumerable<string> Recipients { get; init; }
-
-    /// <summary>
-    /// Email subject
-    /// </summary>
-    public required string Subject { get; init; }
-
-    /// <summary>
-    /// Email body (HTML or plain text)
-    /// </summary>
-    public required string Body { get; init; }
-
-    /// <summary>
-    /// Is HTML email (default: true)
-    /// </summary>
-    public bool IsHtml { get; init; } = true;
-
-    [JsonIgnore]
-    internal IEnumerable<EmailAttachmentContext> Attachments { get; private init; } = [];
-
-    /// <summary>
-    /// Returns a new command instance with the supplied attachments.
-    /// Called by the controller after resolving uploaded files.
-    /// </summary>
-    public SendEmailCommand WithAttachments(IEnumerable<EmailAttachmentContext> attachments)
-        => this with { Attachments = attachments };
-}
-
-/// <summary>
-/// Handler for SendEmailCommand
-/// Resolves the sender account via MediatR, maps to SendingEmailEvent and enqueues to RabbitMQ
-/// </summary>
-public class SendEmailCommandHandler(ISender Sender, ISendingEmailPublisher Publisher, IMapper Mapper) : IRequestHandler<SendEmailCommand, Guid>
-{
-    public async Task<Guid> Handle(SendEmailCommand request, CancellationToken cancellationToken)
-    {
-        var senderAccount = await Sender.Send(request.Sender, cancellationToken)
-            ?? throw new NotFoundException(
-                $"No email account found for the given sender criteria (Id: {request.Sender.Id}, Username: {request.Sender.Username}).");
-
-        var email = Mapper.Map<EmailContext>(request) with { Sender = senderAccount };
-
-        // Enqueue to RabbitMQ
-        var sendingEmailEvent = new SendingEmailEvent()
-        {
-            Id = Guid.NewGuid(),
-            Mail = email,
-            QueuedAt = DateTime.Now
-        };
-        await Publisher.EnqueueAsync(sendingEmailEvent, cancellationToken);
-        return sendingEmailEvent.Id;
-    }
-}

src/core/DigitalData.MessagingService.Application/EmailSending/Validators/SendEmailCommandValidator.cs

@@ -1,14 +1,15 @@
+#if NET
 using DigitalData.MessagingService.Application.EmailSending.Commands;
 using FluentValidation;
 
 namespace DigitalData.MessagingService.Application.EmailSending.Validators;
 
 /// <summary>
-/// Validator for SendEmailCommand
+/// Validator for PublishEmailCommand
 /// </summary>
-public class SendEmailCommandValidator : AbstractValidator<SendEmailCommand>
+public class PublishEmailCommandValidator : AbstractValidator<PublishEmailCommand>
 {
-    public SendEmailCommandValidator()
+    public PublishEmailCommandValidator()
     {
         RuleFor(x => x.Recipients)
             .NotEmpty()
@@ -32,3 +33,4 @@ public class SendEmailCommandValidator : AbstractValidator<SendEmailCommand>
             .WithMessage("Body is required");
     }
 }
+#endif

src/core/DigitalData.MessagingService.Domain/DigitalData.MessagingService.Domain.csproj

@@ -11,4 +11,8 @@
     <PackageReference Include="MediatR" Version="12.2.0" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' == 'net462'">
+    <Reference Include="System.ComponentModel.DataAnnotations" />
+  </ItemGroup>
+
 </Project>

src/core/DigitalData.MessagingService.Domain/Entities/EmailAccount.cs

@@ -0,0 +1,75 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace DigitalData.MessagingService.Domain.Entities;
+
+/// <summary>
+/// DTO for a single email account configuration.
+/// </summary>
+[Table("EMAIL_ACCOUNT")]
+public class EmailAccount
+{
+    /// <summary>
+    /// Logical name to identify this account (e.g. "default", "support").
+    /// </summary>
+    [Key]
+    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+    [Column("ID", TypeName = "int")]
+    public int Id { get; set; }
+
+    [Required]
+    [MaxLength(256)]
+    [Column("USERNAME", TypeName = "nvarchar(256)")]
+#if NET
+    public required string Username { get; set; }
+#else
+    public string Username { get; set; } = null!;
+#endif
+
+    [Required]
+    [MaxLength(512)]
+    [Column("PASSWORD", TypeName = "nvarchar(512)")]
+#if NET
+    public required string Password { get; set; }
+#else
+    public string Password { get; set; } = null!;
+#endif
+
+    [Required]
+    [MaxLength(256)]
+    [Column("SMTP_SERVER", TypeName = "nvarchar(256)")]
+#if NET
+    public required string SmtpServer { get; set; }
+#else
+    public string SmtpServer { get; set; } = null!;
+#endif
+
+    [Column("SMTP_PORT", TypeName = "int")]
+    public int SmtpPort { get; set; }
+
+    [Column("SMTP_USE_SSL", TypeName = "bit")]
+    public bool SmtpUseSsl { get; set; }
+
+    [Column("USE_OAUTH2", TypeName = "bit")]
+    public bool UseOAuth2 { get; set; }
+
+    /// <summary>
+    /// IMAP server hostname (e.g. "imap.example.com").
+    /// Leave empty when this account is send-only.
+    /// </summary>
+    [MaxLength(256)]
+    [Column("IMAP_SERVER", TypeName = "nvarchar(256)")]
+    public string? ImapServer { get; set; }
+
+    /// <summary>
+    /// IMAP server port (993 for SSL, 143 for plain/STARTTLS).
+    /// </summary>
+    [Column("IMAP_PORT", TypeName = "int")]
+    public int ImapPort { get; set; } = 993;
+
+    /// <summary>
+    /// Use SSL/TLS when connecting to the IMAP server.
+    /// </summary>
+    [Column("IMAP_USE_SSL", TypeName = "bit")]
+    public bool ImapUseSsl { get; set; } = true;
+}

src/core/DigitalData.MessagingService.Domain/Entities/EmailAttachment.cs

@@ -0,0 +1,83 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace DigitalData.MessagingService.Domain.Entities;
+
+/// <summary>
+/// Represents a single email attachment.
+/// </summary>
+[Table("EMAIL_ATTACHMENT")]
+public sealed class EmailAttachment
+{
+    [Key]
+    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+    [Column("ID", TypeName = "bigint")]
+#if NET
+    public long Id { get; init; }
+#else
+    public long Id { get; set; }
+#endif
+
+    /// <summary>
+    /// Display name of the attachment (e.g. "invoice.pdf").
+    /// </summary>
+    [Required]
+    [MaxLength(260)]
+    [Column("FILE_NAME", TypeName = "nvarchar(260)")]
+#if NETFRAMEWORK
+    public string FileName { get; set; } = null!;
+#else
+    public required string FileName { get; init; }
+#endif
+
+    /// <summary>
+    /// Raw content of the attachment.
+    /// </summary>
+    [Required]
+    [Column("CONTENT", TypeName = "varbinary(max)")]
+#if NETFRAMEWORK
+    public byte[] Content { get; set; } = null!;
+#else
+    public required byte[] Content { get; init; }
+#endif
+
+    /// <summary>
+    /// MIME content-type (e.g. "application/pdf", "image/png").
+    /// Defaults to "application/octet-stream" when not specified.
+    /// </summary>
+    [Required]
+    [MaxLength(256)]
+    [Column("CONTENT_TYPE", TypeName = "nvarchar(256)")]
+    public string ContentType { get; set; } = "application/octet-stream";
+
+    /// <summary>
+    /// When <see langword="true"/> the attachment is embedded inline and displayed
+    /// directly inside the email body via a CID reference (e.g. &lt;img src="cid:logo"&gt;).
+    /// When <see langword="false"/> (default) it appears as a regular downloadable attachment.
+    /// </summary>
+    [Column("IS_INLINE", TypeName = "bit")]
+    public bool IsInline { get; set; } = false;
+
+    /// <summary>
+    /// Content-ID used when <see cref="IsInline"/> is <see langword="true"/>.
+    /// Reference it in HTML body as <c>cid:{ContentId}</c>.
+    /// Auto-generated from <see cref="FileName"/> when left empty.
+    /// </summary>
+    [MaxLength(512)]
+    [Column("CONTENT_ID", TypeName = "nvarchar(512)")]
+    public string? ContentId { get; set; }
+
+    [ForeignKey(nameof(Email))]
+    [Column("EMAIL_ID", TypeName = "bigint")]
+#if NET
+    public long EmailId { get; init; }
+#else
+    public long EmailId { get; set; }
+#endif
+
+#if NET
+    public ReceivedEmail? Email { get; init; }
+#else
+    public ReceivedEmail? Email { get; set; }
+#endif
+}

src/core/DigitalData.MessagingService.Domain/Entities/ReceivedEmail.cs

@@ -0,0 +1,136 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace DigitalData.MessagingService.Domain.Entities;
+
+/// <summary>
+/// Represents an email message received via IMAP.
+/// </summary>
+[Table("RECEIVED_EMAIL")]
+public sealed record ReceivedEmail
+{
+    [Key]
+    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+    [Column("ID", TypeName = "bigint")]
+#if NET
+    public long Id { get; init; }
+#else
+    public long Id { get; set; }
+#endif
+
+    /// <summary>
+    /// Unique identifier of the message on the IMAP server (UID).
+    /// </summary>
+    [Column("UID", TypeName = "bigint")]
+#if NET
+    public long Uid { get; init; }
+#else
+    public long Uid { get; set; }
+#endif
+
+    /// <summary>
+    /// Sender address (From header).
+    /// </summary>
+    [Required]
+    [MaxLength(512)]
+    [Column("FROM", TypeName = "nvarchar(512)")]
+#if NET
+    public string From { get; init; } = string.Empty;
+#else
+    public string From { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// Recipient addresses (To header).
+    /// </summary>
+    [Column("TO", TypeName = "nvarchar(max)")]
+#if NET
+    public IEnumerable<string> To { get; init; } = [];
+#else
+    public IEnumerable<string> To { get; set; } = [];
+#endif
+
+    /// <summary>
+    /// CC addresses.
+    /// </summary>
+    [Column("CC", TypeName = "nvarchar(max)")]
+#if NET
+    public IEnumerable<string> Cc { get; init; } = [];
+#else
+    public IEnumerable<string> Cc { get; set; } = [];
+#endif
+
+    /// <summary>
+    /// Email subject.
+    /// </summary>
+    [MaxLength(998)]
+    [Column("SUBJECT", TypeName = "nvarchar(998)")]
+#if NET
+    public string Subject { get; init; } = string.Empty;
+#else
+    public string Subject { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// Plain-text body (may be empty when only HTML is present).
+    /// </summary>
+    [Column("TEXT_BODY", TypeName = "nvarchar(max)")]
+#if NET
+    public string TextBody { get; init; } = string.Empty;
+#else
+    public string TextBody { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// HTML body (may be empty when only plain-text is present).
+    /// </summary>
+    [Column("HTML_BODY", TypeName = "nvarchar(max)")]
+#if NET
+    public string HtmlBody { get; init; } = string.Empty;
+#else
+    public string HtmlBody { get; set; } = string.Empty;
+#endif
+
+    /// <summary>
+    /// Date/time the message was sent (Date header).
+    /// </summary>
+    [Column("DATE", TypeName = "datetime2")]
+#if NET
+    public DateTime Date { get; init; }
+#else
+    public DateTime Date { get; set; }
+#endif
+
+    /// <summary>
+    /// Whether the message has been marked as seen/read on the server.
+    /// </summary>
+    [Column("IS_SEEN", TypeName = "bit")]
+#if NET
+    public bool IsSeen { get; init; }
+#else
+    public bool IsSeen { get; set; }
+#endif
+
+    [ForeignKey(nameof(Account))]
+    [Column("ACCOUNT_ID", TypeName = "int")]
+#if NET
+    public int AccountId { get; init; }
+#else
+    public int AccountId { get; set; }
+#endif
+
+    /// <summary>
+    /// Attachments included with this message.
+    /// </summary>
+#if NET
+    public IEnumerable<EmailAttachment>? Attachments { get; init; }
+#else
+    public IEnumerable<EmailAttachment>? Attachments { get; set; }
+#endif
+
+#if NET
+    public EmailAccount? Account { get; init; }
+#else
+    public EmailAccount? Account { get; set; }
+#endif
+}

src/core/DigitalData.MessagingService.Domain/Exceptions/BadRequestException.cs

@@ -0,0 +1,21 @@
+namespace DigitalData.MessagingService.Domain.Exceptions
+{
+    /// <summary>
+    /// Exception thrown when a requested entity is not found.
+    /// </summary>
+    public class BadRequestException : Exception
+    {
+        public BadRequestException(string entityName, object key) : base($"{entityName} with key '{key}' was not found.")
+        {
+        }
+
+        public BadRequestException(string message) : base(message)
+        {
+        }
+
+        public BadRequestException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+    }
+}

src/infrastructure/DigitalData.MessagingService.Infrastructure/DependencyInjection.cs

@@ -1,10 +1,16 @@
+using AutoMapper;
 using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
+using DigitalData.MessagingService.Infrastructure.Mappings;
+using DigitalData.MessagingService.Infrastructure.Persistence;
 using DigitalData.MessagingService.Infrastructure.Queue;
+using DigitalData.MessagingService.Infrastructure.Repositories;
 using DigitalData.MessagingService.Infrastructure.Services;
 using DigitalData.MessagingService.Infrastructure.Services.Background;
 using DigitalData.MessagingService.Publisher;
 using DigitalData.MessagingService.RabbitMQ;
 using Microsoft.AspNetCore.DataProtection;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -23,8 +29,12 @@ public static class DependencyInjection
         IConfiguration configuration)
     {
         // --- External Services ---
-        // Email Service (using Limilabs Mail.dll - Singleton for use in EmailSenderWorker)
+        // Email Service - SMTP outbound (Limilabs Mail.dll)
         services.AddSingleton<IEmailService, LimilabsEmailService>();
+
+        // Email Service - IMAP inbound (Limilabs Mail.dll)
+        // Fresh connection per call — stateless and thread-safe.
+        services.AddSingleton<IImapEmailService, LimilabsImapEmailService>();
         
         // PDF Processing Service (using DevExpress.Pdf)
         services.AddScoped<IPdfProcessingService, DevExpressPdfProcessingService>();
@@ -46,7 +56,20 @@ public static class DependencyInjection
 
         // Register Background Workers
         services.AddHostedService<AsyncInitWorker>();
+        services.AddHostedService<EmailSyncWorker>();
+
+        services.AddMemoryCache();
+
+        // --- Database (InMemory) ---
+        services.AddDbContext<MessagingServiceDbContext>(options =>
+            options.UseInMemoryDatabase("MessagingServiceDb"));
+
+        services.AddScoped(typeof(IRepository<>), typeof(Repository<>));
+
+        // AutoMapper - Register entity self-mappings (T -> T) for generic repository
+        services.AddAutoMapper(config => config.AddMaps(typeof(EntitySelfMappingProfile).Assembly));
 
         return services;
     }
 }
+

src/infrastructure/DigitalData.MessagingService.Infrastructure/DigitalData.MessagingService.Infrastructure.csproj

@@ -25,6 +25,7 @@
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.10" />
     <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="10.0.10" />
     <PackageReference Include="Microsoft.Identity.Client" Version="4.65.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="8.0.11" />
     <PackageReference Include="RabbitMQ.Client" Version="7.2.1" />
     <PackageReference Include="System.Text.Encoding.CodePages" Version="10.0.10" />
   </ItemGroup>

src/infrastructure/DigitalData.MessagingService.Infrastructure/Mappings/EntitySelfMappingProfile.cs

@@ -0,0 +1,19 @@
+using AutoMapper;
+using DigitalData.MessagingService.Domain.Entities;
+
+namespace DigitalData.MessagingService.Infrastructure.Mappings;
+
+/// <summary>
+/// AutoMapper profile that registers self-mappings (T -> T) for all domain entities.
+/// This allows AutoMapper to be used uniformly in the generic repository
+/// regardless of whether TDto is a DTO or the entity type itself.
+/// </summary>
+public class EntitySelfMappingProfile : Profile
+{
+    public EntitySelfMappingProfile()
+    {
+        CreateMap<EmailAccount, EmailAccount>();
+        CreateMap<ReceivedEmail, ReceivedEmail>();
+        CreateMap<EmailAttachment, EmailAttachment>();
+    }
+}

src/infrastructure/DigitalData.MessagingService.Infrastructure/Persistence/MessagingServiceDbContext.cs

@@ -1,11 +1,38 @@
+using DigitalData.MessagingService.Domain.Entities;
 using Microsoft.EntityFrameworkCore;
 
 namespace DigitalData.MessagingService.Infrastructure.Persistence;
 
 /// <summary>
 /// Entity Framework Core DbContext for MessagingService.
-/// IMPORTANT: This context maps to a LEGACY database - NO schema modifications allowed!
 /// </summary>
 public class MessagingServiceDbContext(DbContextOptions<MessagingServiceDbContext> options) : DbContext(options)
 {
+    public DbSet<EmailAccount> EmailAccounts => Set<EmailAccount>();
+    public DbSet<ReceivedEmail> ReceivedEmails => Set<ReceivedEmail>();
+    public DbSet<EmailAttachment> EmailAttachments => Set<EmailAttachment>();
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        base.OnModelCreating(modelBuilder);
+
+        modelBuilder.Entity<EmailAccount>(entity =>
+        {
+            entity.Property(e => e.Username)
+                  .UseCollation("SQL_Latin1_General_CP1_CI_AS");
+        });
+
+        modelBuilder.Entity<ReceivedEmail>(entity =>
+        {
+            entity.HasMany(e => e.Attachments)
+                  .WithOne(a => a.Email)
+                  .HasForeignKey(a => a.EmailId)
+                  .OnDelete(DeleteBehavior.Cascade);
+
+            entity.HasOne(e => e.Account)
+                  .WithMany()
+                  .HasForeignKey(e => e.AccountId)
+                  .OnDelete(DeleteBehavior.Restrict);
+        });
+    }
 }

src/infrastructure/DigitalData.MessagingService.Infrastructure/Queue/SendingEmailConsumer.cs

@@ -1,11 +1,11 @@
 using System.Text;
 using System.Text.Json;
 using DigitalData.MessagingService.Application.Common.Interfaces;
-using DigitalData.MessagingService.Abstraction;
 using DigitalData.MessagingService.RabbitMQ;
 using Microsoft.Extensions.Logging;
 using RabbitMQ.Client;
 using RabbitMQ.Client.Events;
+using DigitalData.MessagingService.Application.Common.Dto;
 
 namespace DigitalData.MessagingService.Infrastructure.Queue;
 

src/infrastructure/DigitalData.MessagingService.Infrastructure/Repositories/Repository.cs

@@ -25,6 +25,14 @@ public class Repository<TEntity>(MessagingServiceDbContext Context, IMapper Mapp
         return entity;
     }
 
+    public async Task<IEnumerable<TEntity>> CreateAsync<TDto>(IEnumerable<TDto> dtos, CancellationToken cancellationToken = default)
+    {
+        var entities = Mapper.Map<IEnumerable<TEntity>>(dtos);
+        await _dbSet.AddRangeAsync(entities, cancellationToken);
+        await Context.SaveChangesAsync(cancellationToken);
+        return entities;
+    }
+
     // --- READ ---
 
     public async Task<TEntity?> GetByIdAsync(int id, CancellationToken cancellationToken = default)
@@ -44,13 +52,13 @@ public class Repository<TEntity>(MessagingServiceDbContext Context, IMapper Mapp
         CancellationToken cancellationToken = default)
     {
         var query = _dbSet.Where(predicate);
-        
+
         if (skip.HasValue)
             query = query.Skip(skip.Value);
-        
+
         if (take.HasValue)
             query = query.Take(take.Value);
-        
+
         return await query.ToListAsync(cancellationToken);
     }
 
@@ -84,6 +92,59 @@ public class Repository<TEntity>(MessagingServiceDbContext Context, IMapper Mapp
         return await _dbSet.AnyAsync(predicate, cancellationToken);
     }
 
+    // --- UPSERT ---
+
+    /// <summary>
+    /// Upsert: if no record matches the predicate, creates a new entity;
+    /// if one or more match, updates the FIRST match.
+    /// Returns the entity and a flag indicating whether it was created (true) or updated (false).
+    /// Auto-saves changes.
+    /// </summary>
+    public async Task<(TEntity Entity, bool Created)> UpsertAsync<TDto>(
+        Expression<Func<TEntity, bool>> predicate,
+        TDto dto,
+        CancellationToken cancellationToken = default)
+    {
+        var entity = await _dbSet.FirstOrDefaultAsync(predicate, cancellationToken);
+
+        if (entity is null)
+        {
+            entity = Mapper.Map<TEntity>(dto);
+            await _dbSet.AddAsync(entity, cancellationToken);
+            await Context.SaveChangesAsync(cancellationToken);
+            return (entity, true);
+        }
+
+        Mapper.Map(dto, entity);
+        await Context.SaveChangesAsync(cancellationToken);
+        return (entity, false);
+    }
+
+    /// <summary>
+    /// Upsert (single-safe): if no record matches the predicate, creates a new entity;
+    /// if exactly one matches, updates it. Throws InvalidOperationException if 2+ match.
+    /// Auto-saves changes.
+    /// </summary>
+    public async Task<(TEntity Entity, bool Created)> UpsertSingleAsync<TDto>(
+        Expression<Func<TEntity, bool>> predicate,
+        TDto dto,
+        CancellationToken cancellationToken = default)
+    {
+        var entity = await _dbSet.SingleOrDefaultAsync(predicate, cancellationToken);
+
+        if (entity is null)
+        {
+            entity = Mapper.Map<TEntity>(dto);
+            await _dbSet.AddAsync(entity, cancellationToken);
+            await Context.SaveChangesAsync(cancellationToken);
+            return (entity, true);
+        }
+
+        Mapper.Map(dto, entity);
+        await Context.SaveChangesAsync(cancellationToken);
+        return (entity, false);
+    }
+
     // --- UPDATE ---
 
     /// <summary>
@@ -96,7 +157,7 @@ public class Repository<TEntity>(MessagingServiceDbContext Context, IMapper Mapp
         TDto dto,
         CancellationToken cancellationToken = default)
     {
-        var entity = await _dbSet.SingleOrDefaultAsync(predicate, cancellationToken) 
+        var entity = await _dbSet.SingleOrDefaultAsync(predicate, cancellationToken)
             ?? throw new NotFoundException($"No {typeof(TEntity).Name} found matching the predicate.");
         Mapper.Map(dto, entity);
         await Context.SaveChangesAsync(cancellationToken);
@@ -113,12 +174,7 @@ public class Repository<TEntity>(MessagingServiceDbContext Context, IMapper Mapp
         CancellationToken cancellationToken = default)
     {
         var entities = await _dbSet.Where(predicate).ToListAsync(cancellationToken);
-
-        foreach (var entity in entities)
-        {
-            Mapper.Map(dto, entity);
-        }
-
+        entities.ForEach(entity => Mapper.Map(dto, entity));
         await Context.SaveChangesAsync(cancellationToken);
         return entities.Count;
     }
@@ -134,7 +190,7 @@ public class Repository<TEntity>(MessagingServiceDbContext Context, IMapper Mapp
         Expression<Func<TEntity, bool>> predicate,
         CancellationToken cancellationToken = default)
     {
-        var entity = await _dbSet.SingleOrDefaultAsync(predicate, cancellationToken) 
+        var entity = await _dbSet.SingleOrDefaultAsync(predicate, cancellationToken)
             ?? throw new NotFoundException($"No {typeof(TEntity).Name} found matching the predicate.");
         _dbSet.Remove(entity);
         await Context.SaveChangesAsync(cancellationToken);
@@ -150,7 +206,6 @@ public class Repository<TEntity>(MessagingServiceDbContext Context, IMapper Mapp
         CancellationToken cancellationToken = default)
     {
         var entities = await _dbSet.Where(predicate).ToListAsync(cancellationToken);
-
         _dbSet.RemoveRange(entities);
         await Context.SaveChangesAsync(cancellationToken);
         return entities.Count;

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/Background/EmailSyncWorker.cs

@@ -0,0 +1,67 @@
+using DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
+using DigitalData.MessagingService.Application.Common.Options;
+using DigitalData.MessagingService.Domain.Entities;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Options;
+
+namespace DigitalData.MessagingService.Infrastructure.Services.Background;
+
+public class EmailSyncWorker(IImapEmailService imapService, IOptions<EmailAccountsOptions> Options, IServiceProvider Provider) : BackgroundService
+{
+    private DateFilter? _dateFilter = null;
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        await UpsertSeedEmailAccount(stoppingToken);
+
+        if (imapService is not LimilabsImapEmailService limapService)
+        {
+            await Task.Delay(Timeout.Infinite, stoppingToken).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);
+            return;
+        }
+
+        var interval = TimeSpan.FromSeconds(Options.Value.SyncIntervalSeconds);
+
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            using var scope = Provider.CreateAsyncScope();
+
+            var emailAccountRepo = scope.ServiceProvider.GetRequiredService<IRepository<EmailAccount>>();
+
+            foreach (var account in await emailAccountRepo.GetAllAsync(stoppingToken))
+                if (account.ImapServer is not null)
+                {
+                    // init or update last date filter
+                    _dateFilter = _dateFilter is null
+                        ? new DateFilter
+                        {
+                            After = null,
+                            Before = DateTime.UtcNow
+                        }
+                        : new DateFilter
+                        {
+                            After = _dateFilter.Before,
+                            Before = DateTime.UtcNow
+                        };
+
+                    await limapService.FetchEmailsAsync(account, new MailSearchFilter { Date = _dateFilter }, stoppingToken);
+                }
+
+            await Task.Delay(interval, stoppingToken).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);
+        }
+    }
+
+    public async Task UpsertSeedEmailAccount(CancellationToken stoppingToken)
+    {
+        using var scope = Provider.CreateAsyncScope();
+
+        var emailAccountRepo = scope.ServiceProvider.GetRequiredService<IRepository<EmailAccount>>();
+
+        // init seed email accounts if not exist
+        foreach (var account in Options.Value.Accounts)
+            await emailAccountRepo.UpsertAsync(a => a.Username == account.Username, account, stoppingToken);
+    }
+}

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/Extensions/ImapExtensions.cs

@@ -0,0 +1,16 @@
+using Limilabs.Client.IMAP;
+
+namespace DigitalData.MessagingService.Infrastructure.Services.Extensions;
+
+public static class ImapExtensions
+{
+    public static async Task CloseSafelyAsync(this Imap imap)
+    {
+        try
+        {
+            if (imap.Connected)
+                await imap.CloseAsync();
+        }
+        catch { /* Ignore disconnect errors */ }
+    }
+}

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/LimilabsEmailService.cs

@@ -5,7 +5,8 @@ using Limilabs.Client.SMTP;
 using Limilabs.Mail;
 using Limilabs.Mail.Headers;
 using DigitalData.MessagingService.Infrastructure.Services.Extensions;
-using DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Domain.Entities;
 
 namespace DigitalData.MessagingService.Infrastructure.Services;
 
@@ -13,11 +14,10 @@ namespace DigitalData.MessagingService.Infrastructure.Services;
 /// Email service using Limilabs Mail.dll for SMTP operations (send-only).
 /// Commercial-grade library with superior Exchange support.
 /// SMTP configuration is injected via IOptions<EmailAccountsOptions> from appsettings.json.
-/// Uses the first account in the list whose <see cref="EmailAccountDto.Name"/> equals <c>"default"</c>,
+/// Uses the first account in the list whose <see cref="EmailAccount.Name"/> equals <c>"default"</c>,
 /// or falls back to the first account if none is named "default".
 /// </summary>
-public class LimilabsEmailService(
-    IEncryptionService encryptionService) : IEmailService
+public class LimilabsEmailService() : IEmailService
 {
     // Register encoding provider for Limilabs (requires windows-1252 and other code pages)
     static LimilabsEmailService()
@@ -71,7 +71,7 @@ public class LimilabsEmailService(
         }
     }
 
-    private async Task ConnectAndAuthenticateSmtpAsync(Smtp smtp, EmailAccountDto smtpAccount)
+    private static async Task ConnectAndAuthenticateSmtpAsync(Smtp smtp, EmailAccount smtpAccount)
     {
         if (smtpAccount.SmtpUseSsl)
         {
@@ -88,9 +88,7 @@ public class LimilabsEmailService(
         }
         else
         {
-            var password = smtpAccount.PasswordEncrypted ? encryptionService.Decrypt(smtpAccount.Password) : smtpAccount.Password;
-
-            await smtp.LoginAsync(smtpAccount.Username, password);
+            await smtp.LoginAsync(smtpAccount.Username, smtpAccount.Password);
         }
     }
 
@@ -111,7 +109,7 @@ public class LimilabsEmailService(
         return message.ToString();
     }
 
-    private static void AddAttachments(MailBuilder builder, IEnumerable<EmailAttachmentContext> attachments)
+    private static void AddAttachments(MailBuilder builder, IEnumerable<EmailAttachmentDto> attachments)
     {
         foreach (var attachment in attachments)
         {

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/LimilabsImapEmailService.cs

@@ -0,0 +1,235 @@
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Dto.MailSearch;
+using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Domain.Entities;
+using DigitalData.MessagingService.Domain.Exceptions;
+using DigitalData.MessagingService.Infrastructure.Services.Extensions;
+using Limilabs.Client.IMAP;
+using Limilabs.Mail;
+using Microsoft.Extensions.Caching.Memory;
+using Microsoft.Extensions.Logging;
+using System.Text;
+
+namespace DigitalData.MessagingService.Infrastructure.Services;
+
+/// <summary>
+/// IMAP email service using Limilabs Mail.dll.
+/// Opens a fresh connection per call — stateless and thread-safe.
+/// </summary>
+public class LimilabsImapEmailService(ILogger<LimilabsImapEmailService> Logger, IMemoryCache Cache) : IImapEmailService
+{
+    private static readonly string CacheKeyPrefix = Guid.NewGuid().ToString();
+
+    static LimilabsImapEmailService()
+    {
+        Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+    }
+
+    // Public API
+    public async Task<IEnumerable<ReceivedEmailDto>> FetchEmailsAsync(
+        EmailAccount account,
+        MailSearchFilter filter,
+        CancellationToken cancel = default)
+    {
+        using var imap = await OpenAsync(account, filter.Folder, cancel);
+        try
+        {
+            #region Find UIDs
+            // Server-side: only date range; all other filters are applied in-process after cache retrieval
+            List<ICriterion> criterions = [];
+
+            if (filter.Date is DateFilter dateF)
+            {
+                if (dateF.After is DateTime after)
+                    criterions.Add(Expression.SentSince(after.Date));
+
+                // IMAP BEFORE is exclusive, so add one day to make the bound inclusive
+                if (dateF.Before is DateTime before)
+                    criterions.Add(Expression.SentBefore(before.Date.AddDays(1)));
+            }
+
+            var searchExpression = criterions.Count > 0 ? Expression.And([.. criterions]) : Expression.All();
+            List<long> uids = [.. await imap.SearchAsync(searchExpression, cancel)];
+
+            if (filter.SortOrder == MailSortOrder.NewestFirst)
+                uids.Reverse();
+            #endregion
+
+            if (uids.Count == 0)
+                return [];
+            
+            var results = new List<ReceivedEmailDto>(uids.Count);
+
+            foreach (var uid in uids)
+            {
+                cancel.ThrowIfCancellationRequested();
+
+                try
+                {
+                    #region Read email
+                    var email = await Cache.GetOrCreateAsync(
+                        CacheKeyPrefix + uid,
+                        async entry =>
+                        {
+                            var eml = await imap.GetMessageByUIDAsync(uid, cancel);
+                            var mail = new MailBuilder().CreateFromEml(eml);
+                            var flags = await imap.GetFlagsByUIDAsync(uid, cancel);
+
+                            var attachments = new List<EmailAttachmentDto>();
+
+                            foreach (var att in mail.Attachments)
+                            {
+                                attachments.Add(new EmailAttachmentDto
+                                {
+                                    FileName = att.FileName ?? "attachment",
+                                    Content = att.Data,
+                                    ContentType = att.ContentType?.ToString() ?? "application/octet-stream",
+                                    IsInline = false,
+                                    ContentId = att.ContentId
+                                });
+                            }
+
+                            foreach (var vis in mail.Visuals)
+                            {
+                                attachments.Add(new EmailAttachmentDto
+                                {
+                                    FileName = vis.FileName ?? "inline",
+                                    Content = vis.Data,
+                                    ContentType = vis.ContentType?.ToString() ?? "application/octet-stream",
+                                    IsInline = true,
+                                    ContentId = vis.ContentId
+                                });
+                            }
+
+                            return new ReceivedEmailDto
+                            {
+                                Uid = uid,
+                                From = mail.From.FirstOrDefault()?.Address ?? string.Empty,
+                                To = [.. mail.To.SelectMany(m => m.GetMailboxes()).Select(mb => mb.Address)],
+                                Cc = [.. mail.Cc.SelectMany(m => m.GetMailboxes()).Select(mb => mb.Address)],
+                                Subject = mail.Subject ?? string.Empty,
+                                TextBody = mail.Text ?? string.Empty,
+                                HtmlBody = mail.Html ?? string.Empty,
+                                Date = mail.Date ?? DateTime.MinValue,
+                                IsSeen = flags.Contains(Flag.Seen),
+                                Attachments = attachments,
+                            };
+                        });
+                    #endregion Read email
+
+                    if (email is null)
+                        continue;
+
+                    if (filter.UnseenOnly && email.IsSeen)
+                        continue;
+
+                    if (filter.SubjectContains is string subject &&
+                        !email.Subject.Contains(subject, StringComparison.OrdinalIgnoreCase))
+                        continue;
+
+                    if (filter.SenderContains is string sender &&
+                        !email.From.Contains(sender, StringComparison.OrdinalIgnoreCase))
+                        continue;
+
+                    if (filter.RecipientContains is string recipient &&
+                        !email.To.Any(t => t.Contains(recipient, StringComparison.OrdinalIgnoreCase)) &&
+                        !email.Cc.Any(c => c.Contains(recipient, StringComparison.OrdinalIgnoreCase)))
+                        continue;
+
+                    if (filter.BodyContains is string body &&
+                        !email.TextBody.Contains(body, StringComparison.OrdinalIgnoreCase) &&
+                        !email.HtmlBody.Contains(body, StringComparison.OrdinalIgnoreCase))
+                        continue;
+
+                    if (filter.Uid is UidFilter uidF)
+                    {
+                        if (uidF.Absolute is long exactUid && email.Uid != exactUid)
+                            continue;
+
+                        if (uidF.Min is long min && email.Uid < min)
+                            continue;
+
+                        if (uidF.Max is long max && email.Uid > max)
+                            continue;
+                    }
+
+                    if (filter.WithAttachments)
+                        results.Add(email);
+                    else
+                        results.Add(email with { Attachments = [] });
+
+                }
+                catch (Exception ex)
+                {
+                    Logger.LogWarning(ex,
+                        "Failed to fetch IMAP message UID={Uid} from folder {Folder}. Skipping.",
+                        uid, filter.Folder);
+                }
+            }
+
+            await imap.CloseAsync(cancel);
+
+            if (filter.MaxCount is int maxCount && maxCount > 0 && results.Count > maxCount)
+                return results.Take(maxCount);
+
+            return results;
+        }
+        catch (Limilabs.Client.ServerException ex)
+        {
+            await imap.CloseSafelyAsync();
+            throw new AuthenticationFailedException(
+                $"IMAP authentication failed for account '{account.Username}'.", ex);
+        }
+        catch (Exception ex) when (ex is not OperationCanceledException)
+        {
+            await imap.CloseSafelyAsync();
+            throw new InvalidOperationException(
+                $"Failed to fetch emails from IMAP server '{account.ImapServer}'.", ex);
+        }
+    }
+
+    public async Task MarkAsSeenAsync(
+        EmailAccount account,
+        long uid,
+        string folder = "INBOX",
+        CancellationToken cancel = default)
+    {
+        using var imap = await OpenAsync(account, folder, cancel);
+        try
+        {
+            await imap.MarkMessageSeenByUIDAsync(uid, cancel);
+            await imap.CloseAsync(cancel);
+        }
+        catch (Limilabs.Client.ServerException ex)
+        {
+            await imap.CloseSafelyAsync();
+            throw new AuthenticationFailedException(
+                $"IMAP authentication failed for account '{account.Username}'.", ex);
+        }
+        catch (Exception ex) when (ex is not OperationCanceledException)
+        {
+            await imap.CloseSafelyAsync();
+            throw new InvalidOperationException(
+                $"Failed to mark message UID={uid} as seen on '{account.ImapServer}'.", ex);
+        }
+    }
+
+    private static async Task<Imap> OpenAsync(EmailAccount account, string folder, CancellationToken cancel)
+    {
+        var imap = new Imap();
+
+        if (account.ImapUseSsl)
+            await imap.ConnectSSLAsync(account.ImapServer!, account.ImapPort, cancel: cancel);
+        else
+            await imap.ConnectAsync(account.ImapServer!, account.ImapPort, cancel: cancel);
+
+        await imap.LoginAsync(account.Username, account.Password, cancel);
+
+        if (string.Equals(folder, "INBOX", StringComparison.OrdinalIgnoreCase))
+            await imap.SelectInboxAsync(cancel);
+        else
+            await imap.SelectAsync(folder, cancel);
+
+        return imap;
+    }
+}

src/infrastructure/DigitalData.MessagingService.Publisher/DependencyInjection.cs

@@ -1,6 +1,5 @@
-using DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Application.Common.Interfaces;
 using DigitalData.MessagingService.RabbitMQ;
-using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace DigitalData.MessagingService.Publisher;

src/infrastructure/DigitalData.MessagingService.Publisher/DigitalData.MessagingService.Publisher.csproj

@@ -12,7 +12,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\core\DigitalData.MessagingService.Abstraction\DigitalData.MessagingService.Abstraction.csproj" />
+    <ProjectReference Include="..\..\core\DigitalData.MessagingService.Application\DigitalData.MessagingService.Application.csproj" />
     <ProjectReference Include="..\DigitalData.MessagingService.RabbitMQ\DigitalData.MessagingService.RabbitMQ.csproj" />
   </ItemGroup>
 

src/infrastructure/DigitalData.MessagingService.Publisher/SendingEmailPublisher.cs

@@ -4,7 +4,8 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using RabbitMQ.Client;
 using DigitalData.MessagingService.RabbitMQ;
-using DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Interfaces;
 
 namespace DigitalData.MessagingService.Publisher;
 

src/presentation/DigitalData.MessagingService.API/Controllers/EmailAccountController.cs

@@ -0,0 +1,27 @@
+using DigitalData.MessagingService.Application.EmailAccounts.Queries;
+using MediatR;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DigitalData.MessagingService.API.Controllers;
+
+/// <summary>
+/// 
+/// </summary>
+[Route("api/[controller]")]
+[ApiController]
+public class EmailAccountController(IMediator mediator) : ControllerBase
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="query"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    [HttpGet]
+    [ProducesResponseType(StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<IActionResult> GetEmailAccount([FromQuery] GetEmailAccountQuery query, CancellationToken cancellationToken)
+    {
+        return Ok(await mediator.Send(query, cancellationToken));
+    }
+}

src/presentation/DigitalData.MessagingService.API/Controllers/EmailController.cs

@@ -0,0 +1,115 @@
+using DigitalData.MessagingService.Application.EmailSending.Commands;
+using DigitalData.MessagingService.Application.EmailReceiving.Queries;
+using MediatR;
+using Microsoft.AspNetCore.Mvc;
+using DigitalData.MessagingService.Application.Common.Dto;
+
+namespace DigitalData.MessagingService.API.Controllers;
+
+/// <summary>
+/// Email sending API controller.
+/// Enqueues outgoing emails to RabbitMQ for async processing.
+/// </summary>
+[ApiController]
+[Route("api/[controller]")]
+public class EmailController(IMediator mediator) : ControllerBase
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public enum OnlyFilter
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        HtmlBody,
+        /// <summary>
+        /// 
+        /// </summary>
+        Uid,
+    }
+
+    #region Send
+    /// <summary>
+    /// Send an email, optionally with file attachments.
+    /// Omit the <c>attachments</c> field for a plain send.
+    /// </summary>
+    /// <param name="command">Email fields as form values</param>
+    /// <param name="attachments">Optional uploaded files</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>HTTP 202 Accepted with the queued event ID</returns>
+    [HttpPost]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(StatusCodes.Status202Accepted)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    public async Task<IActionResult> SendEmail(
+        [FromForm] PublishEmailCommand command,
+        IFormFileCollection? attachments,
+        CancellationToken cancellationToken)
+    {
+        var commandWithAttachments = command.WithAttachments(
+            await BuildAttachmentsAsync(attachments, cancellationToken));
+
+        var eventId = await mediator.Send(commandWithAttachments, cancellationToken);
+        return Accepted(new { Id = eventId });
+    }
+
+    private static async Task<IEnumerable<EmailAttachmentDto>> BuildAttachmentsAsync(
+        IFormFileCollection? files,
+        CancellationToken cancellationToken)
+    {
+        if (files is null || files.Count == 0)
+            return [];
+
+        var result = new List<EmailAttachmentDto>(files.Count);
+
+        foreach (var file in files)
+        {
+            using var ms = new MemoryStream();
+            await file.CopyToAsync(ms, cancellationToken);
+
+            result.Add(new EmailAttachmentDto
+            {
+                FileName    = file.FileName,
+                Content     = ms.ToArray(),
+                ContentType = file.ContentType
+            });
+        }
+
+        return result;
+    }
+    #endregion Send
+
+    #region Receive
+    /// <summary>
+    /// Fetch emails from an IMAP mailbox.
+    /// </summary>
+    /// <param name="query">Query parameters for filtering and fetching emails from the IMAP mailbox.</param>
+    /// <param name="only"></param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>HTTP 200 with list of received emails.</returns>
+    [HttpGet]
+    [ProducesResponseType(StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<IActionResult> FetchEmails([FromQuery] FetchEmailsQuery query, [FromQuery] OnlyFilter? only = null, CancellationToken cancellationToken = default)
+    {
+        var emails = await mediator.Send(query, cancellationToken);
+
+        if(!emails.Any())
+            return NotFound("No emails found matching the specified criteria.");
+
+        if (only == OnlyFilter.HtmlBody)
+        {
+            if (emails.FirstOrDefault()?.HtmlBody is string htmlBody)
+                return Content(htmlBody, "text/html");
+            else
+                return NotFound();
+        }
+        else if (only == OnlyFilter.Uid)
+            return Ok(emails.Select(e => e.Uid).ToList());
+        else
+            return Ok(emails);
+    }
+    #endregion Receive
+}

src/presentation/DigitalData.MessagingService.API/Controllers/EmailsController.cs

@@ -1,64 +0,0 @@
-using DigitalData.MessagingService.Application.EmailSending.Commands;
-using DigitalData.MessagingService.Abstraction;
-using MediatR;
-using Microsoft.AspNetCore.Mvc;
-
-namespace DigitalData.MessagingService.API.Controllers;
-
-/// <summary>
-/// Email sending API controller.
-/// Enqueues outgoing emails to RabbitMQ for async processing.
-/// </summary>
-[ApiController]
-[Route("api/[controller]")]
-public class EmailsController(IMediator mediator) : ControllerBase
-{
-    /// <summary>
-    /// Send an email, optionally with file attachments.
-    /// Omit the <c>attachments</c> field for a plain send.
-    /// </summary>
-    /// <param name="command">Email fields as form values</param>
-    /// <param name="attachments">Optional uploaded files</param>
-    /// <param name="cancellationToken">Cancellation token</param>
-    /// <returns>HTTP 202 Accepted with the queued event ID</returns>
-    [HttpPost]
-    [Consumes("multipart/form-data")]
-    [ProducesResponseType(StatusCodes.Status202Accepted)]
-    [ProducesResponseType(StatusCodes.Status400BadRequest)]
-    public async Task<IActionResult> SendEmail(
-        [FromForm] SendEmailCommand command,
-        IFormFileCollection? attachments,
-        CancellationToken cancellationToken)
-    {
-        var commandWithAttachments = command.WithAttachments(
-            await BuildAttachmentsAsync(attachments, cancellationToken));
-
-        var eventId = await mediator.Send(commandWithAttachments, cancellationToken);
-        return Accepted(new { Id = eventId });
-    }
-
-    private static async Task<IEnumerable<EmailAttachmentContext>> BuildAttachmentsAsync(
-        IFormFileCollection? files,
-        CancellationToken cancellationToken)
-    {
-        if (files is null || files.Count == 0)
-            return [];
-
-        var result = new List<EmailAttachmentContext>(files.Count);
-
-        foreach (var file in files)
-        {
-            using var ms = new MemoryStream();
-            await file.CopyToAsync(ms, cancellationToken);
-
-            result.Add(new EmailAttachmentContext
-            {
-                FileName    = file.FileName,
-                Content     = ms.ToArray(),
-                ContentType = file.ContentType
-            });
-        }
-
-        return result;
-    }
-}

src/presentation/DigitalData.MessagingService.API/Middleware/ExceptionHandlingMiddleware.cs

@@ -1,89 +1,82 @@
 using System.Net;
 using System.Text.Json;
 using DigitalData.MessagingService.Domain.Exceptions;
+using FluentValidation;
 
 namespace DigitalData.MessagingService.API.Middleware;
 
 /// <summary>
 /// Global exception handling middleware
 /// </summary>
-public class ExceptionHandlingMiddleware
+public class ExceptionHandlingMiddleware(RequestDelegate Next, ILogger<ExceptionHandlingMiddleware> Logger)
 {
     private static readonly JsonSerializerOptions _jsonSerializerOptions = new()
     {
         PropertyNamingPolicy = JsonNamingPolicy.CamelCase
     };
 
-    private readonly RequestDelegate _next;
-    private readonly ILogger<ExceptionHandlingMiddleware> _logger;
-
-    public ExceptionHandlingMiddleware(
-        RequestDelegate next,
-        ILogger<ExceptionHandlingMiddleware> logger)
-    {
-        _next = next;
-        _logger = logger;
-    }
-
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="context"></param>
+    /// <returns></returns>
     public async Task InvokeAsync(HttpContext context)
     {
         try
         {
-            await _next(context);
+            await Next(context);
         }
         catch (Exception ex)
         {
-            await HandleExceptionAsync(context, ex);
+            context.Response.ContentType = "application/json";
+
+            var (statusCode, message) = ex switch
+            {
+                NotFoundException notFoundEx =>
+                    (HttpStatusCode.NotFound, notFoundEx.Message),
+
+                BadRequestException badRequestEx =>
+                    (HttpStatusCode.BadRequest, badRequestEx.Message),
+
+                AuthenticationFailedException authEx =>
+                    (HttpStatusCode.Unauthorized, authEx.Message),
+
+                ValidationException validationEx =>
+                    (HttpStatusCode.BadRequest, FormatValidationErrors(validationEx)),
+
+                _ => (HttpStatusCode.InternalServerError, "An internal server error occurred")
+            };
+
+            context.Response.StatusCode = (int)statusCode;
+
+            // Log the exception
+            if (statusCode == HttpStatusCode.InternalServerError)
+            {
+                Logger.LogError(ex, "Unhandled exception: {Message}", ex.Message);
+            }
+            else
+            {
+                Logger.LogWarning(ex, "Exception handled: {StatusCode} - {Message}",
+                    statusCode, message);
+            }
+
+            var response = new
+            {
+                StatusCode = (int)statusCode,
+                Message = message,
+                DetailedMessage = statusCode == HttpStatusCode.InternalServerError
+                    ? ex.Message
+                    : null,
+                Timestamp = DateTime.Now
+            };
+
+            var json = JsonSerializer.Serialize(response, _jsonSerializerOptions);
+
+            await context.Response.WriteAsync(json);
         }
     }
 
-    private async Task HandleExceptionAsync(HttpContext context, Exception exception)
-    {
-        context.Response.ContentType = "application/json";
-
-        var (statusCode, message) = exception switch
-        {
-            NotFoundException notFoundEx => 
-                (HttpStatusCode.NotFound, notFoundEx.Message),
-            
-            AuthenticationFailedException authEx => 
-                (HttpStatusCode.Unauthorized, authEx.Message),
-                        
-            FluentValidation.ValidationException validationEx =>
-                (HttpStatusCode.BadRequest, FormatValidationErrors(validationEx)),
-            
-            _ => (HttpStatusCode.InternalServerError, "An internal server error occurred")
-        };
-
-        context.Response.StatusCode = (int)statusCode;
-
-        // Log the exception
-        if (statusCode == HttpStatusCode.InternalServerError)
-        {
-            _logger.LogError(exception, "Unhandled exception: {Message}", exception.Message);
-        }
-        else
-        {
-            _logger.LogWarning(exception, "Exception handled: {StatusCode} - {Message}", 
-                statusCode, message);
-        }
-
-        var response = new
-        {
-            StatusCode = (int)statusCode,
-            Message = message,
-            DetailedMessage = statusCode == HttpStatusCode.InternalServerError 
-                ? exception.Message 
-                : null,
-            Timestamp = DateTime.Now
-        };
-
-        var json = JsonSerializer.Serialize(response, _jsonSerializerOptions);
-
-        await context.Response.WriteAsync(json);
-    }
-
-    private static string FormatValidationErrors(FluentValidation.ValidationException exception)
+    private static string FormatValidationErrors(ValidationException exception)
     {
         var errors = exception.Errors
             .Select(e => $"{e.PropertyName}: {e.ErrorMessage}")

src/presentation/DigitalData.MessagingService.Client/DigitalData.MessagingService.Client.csproj

@@ -35,9 +35,6 @@
 	</ItemGroup>
 
 	<ItemGroup>
-	  <ProjectReference Include="..\..\core\DigitalData.MessagingService.Abstraction\DigitalData.MessagingService.Abstraction.csproj">
-	    <PrivateAssets>all</PrivateAssets>
-	  </ProjectReference>
 	  <ProjectReference Include="..\..\infrastructure\DigitalData.MessagingService.Publisher\DigitalData.MessagingService.Publisher.csproj">
 	    <PrivateAssets>all</PrivateAssets>
 	  </ProjectReference>

src/presentation/DigitalData.MessagingService.Client/EmailSender.cs

@@ -1,7 +1,8 @@
 using DigitalData.MessagingService.Publisher;
-using DigitalData.MessagingService.Abstraction;
 using DigitalData.MessagingService.RabbitMQ;
 using Microsoft.Extensions.DependencyInjection;
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Interfaces;
 
 namespace DigitalData.MessagingService.Client;
 

tests/DigitalData.MessagingService.Tests/Integration/EmailSenderTests.cs

@@ -1,5 +1,6 @@
+using DigitalData.MessagingService.Application.Common.Dto;
 using DigitalData.MessagingService.Client;
-using DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Domain.Entities;
 
 namespace DigitalData.MessagingService.Tests.Integration;
 
@@ -77,7 +78,7 @@ public sealed class EmailSenderTests
     {
         var email = new EmailContext
         {
-            Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+            Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
             Recipients = ["hakanttek@gmail.com"],
             Subject = "EmailSender.Send Integration Test",
             Body = "<p>Sent via EmailSender static client.</p>",
@@ -94,7 +95,7 @@ public sealed class EmailSenderTests
     {
         var email = new EmailContext
         {
-            Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+            Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
             Recipients = ["hakanttek@gmail.com"],
             Subject = "Plain Text Test",
             Body = "This is a plain text email.",

tests/DigitalData.MessagingService.Tests/Integration/EmailSenderUrlOverloadTests.cs

@@ -1,5 +1,6 @@
+using DigitalData.MessagingService.Application.Common.Dto;
 using DigitalData.MessagingService.Client;
-using DigitalData.MessagingService.Abstraction;
+using DigitalData.MessagingService.Domain.Entities;
 
 namespace DigitalData.MessagingService.Tests.Integration;
 
@@ -57,7 +58,7 @@ public sealed class EmailSenderUrlOverloadTests
     {
         var email = new EmailContext
         {
-            Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+            Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
             Recipients = ["url-overload-test@example.com"],
             Subject = "URL Overload Integration Test",
             Body = "<p>Sent after URL-based connection.</p>",

tests/DigitalData.MessagingService.Tests/Integration/SendingEmailPublisherTests.cs

@@ -1,11 +1,11 @@
 using System.Text;
 using System.Text.Json;
 using DigitalData.MessagingService.Publisher;
-using DigitalData.MessagingService.Abstraction;
 using DigitalData.MessagingService.RabbitMQ;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging;
-using RabbitMQ.Client;
+using DigitalData.MessagingService.Application.Common.Dto;
+using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Domain.Entities;
 
 namespace DigitalData.MessagingService.Tests.Integration;
 
@@ -39,7 +39,7 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = Guid.NewGuid(),
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
                 Recipients = ["test@example.com"],
                 Subject = "Integration Test - EnqueueAsync",
                 Body = "<p>Hello from integration test.</p>",
@@ -68,8 +68,8 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = Guid.NewGuid(),
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
-                Recipients = new List<string> { $"recipient{i}@example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Recipients = [$"recipient{i}@example.com"],
                 Subject = $"Integration Test - Batch #{i}",
                 Body = $"Batch message {i}",
                 IsHtml = false,
@@ -95,7 +95,7 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = Guid.NewGuid(),
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
                 Recipients = ["depth-test@example.com"],
                 Subject = "Integration Test - GetQueueDepth",
                 Body = "Queue depth test",
@@ -122,7 +122,7 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = id,
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
                 Recipients = new List<string> { "serialize@example.com" },
                 Subject = "Serialization Test",
                 Body = "<strong>Bold</strong>",