OL2002: Modifying a Plain Text Message Using IMAP Results in a Winmail.dat File Attachment (280857)

SYMPTOMS

When you modify a plain text message in your IMAP mailbox and then download the message by using an e-mail program other than Outlook, a Winmail.dat attachment appears.

CAUSE

This behavior occurs because changing the message body or subject line and then saving the message causes the message to be encoded in Transport Neutral Encapsulation Format (TNEF). Messages that are formatted in Rich Text Format or that contain Outlook items are typically TNEF-encoded. Modifying a plain text message on an IMAP server with Outlook 2002 also causes a message to be TNEF-encoded. When a message that contains TNEF information is received by a mail client that does not understand TNEF, an attachment named Winmail.dat may be created.

WORKAROUND

To work around this issue, just ignore the Winmail.dat attachment, which contains formatting information that only Outlook can interpret. The recipient receives the plain text version of the message you modified.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

290809 How Message Formats Affect Internet Mail