Ich habe nochmal nachgeschaut, die Mails sind nicht über den Mailserver gelaufen, der mit Trend die Mails scannt. Aber ich habe noch was gefunden :
Problem:
It has been found that, when customer receive messages with attachments sent from MS Exchange users, the attachments received sometimes become WINMAIL.DAT, with the application type being MS-TNEF.
Solution:
This issue has been reported to Lotus Quality Engineering.
The problem is due to messages being sent from MS Exchange without MIME encoding turned on. WINMAIL.DAT is attached to the message in UUENCODED format. Information on how to prevent Winmail data being sent to Internet users from MS Exchange is documented and publicly available from the Microsoft Support Web page, in the Microsoft Knowledge Base, article number Q138053.
Insofern hat es was damit zu tun, dass es eben nicht MIME Format hat, da kann ich dann höchstens einstellen "keine Änderungen", die Frage ist nur, was macht der SMTP Server draus.
Meff