All versions of Microsoft Outlook, including Outlook 2010, its most recent offering as of December 2011, sometimes add a winmail.dat file to a sent email. The file contains information for the Microsoft Outlook rich text format when the sender of the email has Outlook set to use Word as the email editor. People who have email software programs that don’t support Microsoft’s proprietary formats will receive the email message in plain text and with an attachment, winmail.dat.
Winmail.dat
- Depending upon the email software used by people with whom you communicate, Microsoft Outlook may attach a file, winmail.dat, that contains formatting information, and sometimes other attachments you sent along in the email, if you sent the original email in rich text format and the receiving system doesn’t have RTF as an option. Microsoft uses a proprietary process to format its emails, and for systems not set to “read” the format, Outlook sends the formatting info separately. It will also bundle up any email attachments, such as photos or documents, in the winmail.dat file in these cases.
Plain Text
- When you communicate with someone who has a different email software program, set the email to send a plain text message. Most email programs can receive emails in plain text, and the receiver of the email will see it in his chosen default font. Click Format in the Outlook menu bar and then select Plain Text to configure the email before sending.
Changing Default Settings
- Change your default settings in Outlook so that it doesn’t send the winmail.dat file along with your rich text emails. Navigate to Tools, then Options, and click the Mail Format tab. Set the default setting to Plain Text or HTML, which is Hypertext Markup Language. Using HTML makes links active in sent emails. The best setting is the one that lets Outlook decide on the format, as Outlook can automatically detect the format needed by the recipient.
Received Email
- If you don’t use Outlook software to send and receive emails, when you receive an email with attachments from an Outlook user you can ask the sender to resend in plain text format. That way you will receive the attachments without having to use software to decode them. The other option is to download one of three free software packages available to decode the winmail.dat extension: Fentun, TNEF’s Enough and EOLSoft’s Winmail Opener.
