diff --git a/Jobs/EDMI/ZUGFeRD/ImportZUGFeRDFiles.vb b/Jobs/EDMI/ZUGFeRD/ImportZUGFeRDFiles.vb
index 33b292ab..5f066ed4 100644
--- a/Jobs/EDMI/ZUGFeRD/ImportZUGFeRDFiles.vb
+++ b/Jobs/EDMI/ZUGFeRD/ImportZUGFeRDFiles.vb
@@ -117,7 +117,10 @@ Public Class ImportZUGFeRDFiles
     End Sub
 
     Private Function GetMessageIdFromFileName(Filename As String) As String
-        Dim oMatch = Regex.Match(Filename, "([\w\d]+)~.+", RegexOptions.IgnoreCase)
+        ' Regex to find MessageId
+        ' See also: https://stackoverflow.com/questions/3968500/regex-to-validate-a-message-id-as-per-rfc2822
+        Dim oRegex = "(((([a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+(\.[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)*)|(""(([\x01-\x08\x0B\x0C\x0E-\x1F\x7F]|[\x21\x23-\x5B\x5D-\x7E])|(\\[\x01-\x09\x0B\x0C\x0E-\x7F]))*""))@(([a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+(\.[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)*)|(\[(([\x01-\x08\x0B\x0C\x0E-\x1F\x7F]|[\x21-\x5A\x5E-\x7E])|(\\[\x01-\x09\x0B\x0C\x0E-\x7F]))*\]))))~.+"
+        Dim oMatch = Regex.Match(Filename, oRegex, RegexOptions.IgnoreCase)
 
         If oMatch.Success Then
             Dim oMessageId = oMatch.Groups(1).Value
@@ -206,6 +209,11 @@ Public Class ImportZUGFeRDFiles
                                 oMissingProperties = New List(Of String)
                                 oCurrentFileCount += 1
 
+                                If Not oFile.Name.EndsWith(".pdf") Then
+                                    _logger.Debug("Skipping non-pdf file {0}", oFile.Name)
+                                    Continue For
+                                End If
+
                                 _logger.Info("Start processing file {0}", oFile.Name)
 
                                 Try