diff --git a/src/presentation/DigitalData.MessagingService.API/Controllers/OAuth2Controller.cs b/src/presentation/DigitalData.MessagingService.API/Controllers/OAuth2Controller.cs
index 13a9a7d..d7b3b78 100644
--- a/src/presentation/DigitalData.MessagingService.API/Controllers/OAuth2Controller.cs
+++ b/src/presentation/DigitalData.MessagingService.API/Controllers/OAuth2Controller.cs
@@ -20,20 +20,20 @@ public class OAuth2Controller(IMediator mediator, IHttpContextAccessor httpConte
     /// Step 1: Redirects the user to Google's consent screen for the specified email account.
     /// After consent, Google redirects to <c>/api/oauth2/google/callback</c> with an authorization code.
     /// </summary>
-    /// <param name="accountId">ID of the email account to authorize.</param>
+    /// <param name="username">the email account to authorize.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
     /// <returns>HTTP 302 redirect to Google consent screen.</returns>
-    [HttpGet("google/authorize/{accountId:int}")]
+    [HttpGet("google/authorize/{username}")]
     [ProducesResponseType(StatusCodes.Status302Found)]
     [ProducesResponseType(StatusCodes.Status400BadRequest)]
     [ProducesResponseType(StatusCodes.Status404NotFound)]
-    public async Task<IActionResult> AuthorizeGoogle(int accountId, CancellationToken cancellationToken)
+    public async Task<IActionResult> AuthorizeGoogle([FromRoute] string username, CancellationToken cancellationToken)
     {
         var redirectUri = BuildCallbackUri();
 
         var authUrl = await mediator.Send(new GetOAuth2AuthorizationUrlQuery
         {
-            AccountId   = accountId,
+            Username = username,
             RedirectUri = redirectUri
         }, cancellationToken);
 
diff --git a/src/presentation/DigitalData.MessagingService.API/Controllers/SyncController.cs b/src/presentation/DigitalData.MessagingService.API/Controllers/SyncController.cs
index c5e59be..c29581d 100644
--- a/src/presentation/DigitalData.MessagingService.API/Controllers/SyncController.cs
+++ b/src/presentation/DigitalData.MessagingService.API/Controllers/SyncController.cs
@@ -1,6 +1,5 @@
-using DigitalData.MessagingService.Infrastructure.Services.Background;
+using DigitalData.MessagingService.Application.Common.Interfaces;
 using Microsoft.AspNetCore.Mvc;
-using Microsoft.Extensions.Hosting;
 
 namespace DigitalData.MessagingService.API.Controllers;
 
@@ -9,7 +8,7 @@ namespace DigitalData.MessagingService.API.Controllers;
 /// </summary>
 [ApiController]
 [Route("api/[controller]")]
-public class SyncController(IEnumerable<IHostedService> hostedServices) : ControllerBase
+public class SyncController(IEmailSyncService emailSyncService) : ControllerBase
 {
     /// <summary>
     /// Triggers an immediate email sync cycle for all configured accounts,
@@ -22,14 +21,7 @@ public class SyncController(IEnumerable<IHostedService> hostedServices) : Contro
     [ProducesResponseType(StatusCodes.Status503ServiceUnavailable)]
     public IActionResult TriggerSync()
     {
-        var syncWorker = hostedServices.OfType<EmailSyncWorker>().FirstOrDefault();
-
-        if (syncWorker is null)
-            return StatusCode(StatusCodes.Status503ServiceUnavailable,
-                new { Message = "EmailSyncWorker is not running." });
-
-        syncWorker.TriggerSync();
-
-        return Accepted(new { Message = "Sync triggered. The next cycle will start immediately." });
+        var syncTime = emailSyncService.ForceTriggerSync();
+        return Accepted(new { syncTime });
     }
 }
diff --git a/src/presentation/DigitalData.MessagingService.API/Program.cs b/src/presentation/DigitalData.MessagingService.API/Program.cs
index 2e37be9..65a1537 100644
--- a/src/presentation/DigitalData.MessagingService.API/Program.cs
+++ b/src/presentation/DigitalData.MessagingService.API/Program.cs
@@ -69,7 +69,35 @@ try
     builder.Services.AddControllers();
 
     builder.Services.AddEndpointsApiExplorer();
-    builder.Services.AddSwaggerGen();
+    builder.Services.AddSwaggerGen(options =>
+    {
+        options.SwaggerDoc("v1", new Microsoft.OpenApi.Models.OpenApiInfo
+        {
+            Title = "DigitalData MessagingService API",
+            Version = "v1",
+            Description = """
+                Die **DigitalData MessagingService API** stellt Endpunkte zur Verwaltung von E-Mail-Konten,
+                E-Mail-Profilen sowie zur Verarbeitung und Nachverfolgung eingehender und ausgehender Nachrichten bereit.
+
+                ---
+
+                ## Authentifizierung
+
+                Für OAuth2-geschützte Endpunkte ist eine Authentifizierung erforderlich.
+                Rufen Sie den folgenden Endpunkt auf und ersetzen Sie `{E-Mail-Adresse}` durch die zu authentifizierende E-Mail-Adresse:
+
+                `/api/OAuth2/google/authorize/{E-Mail-Adresse}`
+
+                **Beispiel:** **[/api/OAuth2/google/authorize/htek0100@gmail.com &rarr;](/api/OAuth2/google/authorize/htek0100@gmail.com)**
+
+                ---
+
+                ## Weiterführende Links
+
+                - [Serilog Log-Viewer &nearr;](/serilog-ui)
+                """
+        });
+    });
 
     // Required by OAuth2Controller to build callback URIs
     builder.Services.AddHttpContextAccessor();
@@ -92,14 +120,30 @@ try
     // Add Serilog request logging
     app.UseSerilogRequestLogging();
 
-    // Configure Swagger — enabled in Development always, and in other environments based on appsettings
+    // Configure Swagger � enabled in Development always, and in other environments based on appsettings
     var swaggerEnabled = app.Environment.IsDevelopment()
         || app.Configuration.GetValue<bool>("Swagger:Enabled");
 
     if (swaggerEnabled)
     {
         app.UseSwagger();
-        app.UseSwaggerUI();
+        app.UseSwaggerUI(ui =>
+        {
+            ui.SwaggerEndpoint("/swagger/v1/swagger.json", "DigitalData MessagingService API v1");
+            // Inject CSS so all description links open in a new tab
+            ui.InjectStylesheet("data:text/css,.renderedMarkdown a{target:_blank}");
+            ui.InjectJavascript("data:text/javascript," + Uri.EscapeDataString("""
+                window.addEventListener('load', () => {
+                    const observer = new MutationObserver(() => {
+                        document.querySelectorAll('.renderedMarkdown a').forEach(a => {
+                            a.setAttribute('target', '_blank');
+                            a.setAttribute('rel', 'noopener noreferrer');
+                        });
+                    });
+                    observer.observe(document.body, { childList: true, subtree: true });
+                });
+                """));
+        });
     }
 
     app.UseHttpsRedirection();