Problems sending attachments through MDaemon

Users receive winmail.dat attachments on emails from MDaemon.

When mail containing a file attachment is sent through MDaemon, it relays the message exactly as it was received. No change is made to the attachment unless it is an inbound message, and MDaemon has been configured to automatically extract encoded file attachments. MDaemon can also be configured to strip attachments via the content filter settings, but by default it leaves the message intact.

Certain Microsoft mail client software that utilizes the proprietary Rich Text Format will designate the Content-Type: of attachments as MS-TNEF when the Rich Text Format option is enabled. Most mail clients, including Microsoft’s Outlook Express, do not recognize this content type.  The result is that attachments that were sent from a client with this feature enabled will not be recognizable to a mail client without this capability. The only known solution to this problem is to disable the Rich Text Format setting before sending mail with attachments.

In Microsoft Outlook, this option can be changed by following these steps.

  1. Click Tools.
  2. Click Options.
  3. Change the 'Compose message in this format' to HTML or Plain Text.
  4. Click Apply.
  5. Click OK.