What are winmail.dat Files?

Sometimes emails received with or without attachments will show up with a "winmail.dat" file as an attachment. The reason for this is that Microsoft Outlook sends the message using RTF format for bold text and other text enhancements and includes the formatting commands in a winmail.dat file. Receiving email clients that do not understand the file display it as a stale attachment. To make matters worse, Outlook may also pack other, regular file attachments in the winmail.dat file.

To prevent winmail.dat attachments from being sent in Outlook, follow these simple steps:

1. Select Tools from the menu.

2. Select Options.

3. Select the Mail Format tab.

4. Under Compose in this message format:, make sure either HTML or Plain Text is selected.

5. Click Internet Format and make sure that either Convert to Plain Text format or Convert to HTML format is selected under When sending Outlook Rich Text messages to Internet recipients, use this format.

6. Click OK and then OK again.