Do recipients of your emails, seemingly out of the blue, complain about a mysterious attachment called “winmail.dat” (of the evermore mysterious content type “application.ms-tnef”), which they cannot open, no matter what they try? Do files you attach disappear in that winmail.dat moloch? Does winmail.dat show up for some but not all recipients of your message?
When, How and Why Winmail.dat-Application.MS-Tnef is Created
It’s Outllok’s fault, in a way. Or the recipient’s email client’s. If Outlook sends a message using the RTF (which is very common outside Outlook) for bold text and other text enhancements, it includes the formatting commands in the winmail.dat file. Receiving email clients that do not understand the code therin display it as a stale attachment. To make matters worse, Outlook may also pack other, regular file attachments in the winmail.dat file.
Fortunately, you can get rid of winmail.dat alltogether by making sure Outlook does not even try to send email using RTF.
Prevent Winmail.dat Attachments from Being Sent in Outlook
To prevent Outlook (2003) from attaching winmail.dat when you send an email:
1. Select Tools, Options from the menu
2. Go to the “Mail Format” tab and ensure either “HTML” or “Plain Text” is selected.
3. On the “Mail Format” tab, select the “Internet Format” button and ensure that either “Convert to Plain Text Format” or “Convert to HTML Format” is selected. Click OK, then OK again.
