Attachments Coming as Winmail.dat

thoughtful black businesswoman working on project in office

A reader is having an annoying email problem:

I use Windows 10 on a desktop PC and have a purchased copy of Microsoft Office 2019. I use MS Outlook for my emails and have had no problem until recently. Whenever I send to a contact a .doc, .docx, .jpg attachment, it comes out in the contact’s inbox as winmail.dat, not the name of the file as I had sent it. They cannot open it!!! My sister-in-law has the same setup as I do and receives the winmail.dat attachments. I have been reading some hints saying to use HTML for composing emails, which I have always done, not been changed. All this has happened since the last Windows 10 update, or am I imagining that? I have been a PC user since 1990 and have never had this problem. Can you please offer any suggestions to rectify this -it is most annoying. Thanks very much.”

This issue happens when you compose your email using rich text instead of plain text. Rich text can have formatting like bold or italic text. The winmail.dat attachments are instructions for the recipient’s email on how to format that information. The way to fix this is to send the messages in plain text or HTML. If this only happened since the last update, it’s possible your Outlook reset to the RTF (rich text format.) Let’s look at how to change that.

Open Outlook and click on File at the top.

Then choose Options from the lower left.

Click Mail and then make sure you’ve selected HTML or Plain Txt.

Let me know if this helps.

One thought on “Attachments Coming as Winmail.dat

  1. Thank you so much, Cyn, for posting this reply! I, too, have had problems with that “.dat” extension and now I know why. I thought all along that “rich text” was the way to go. Now I know better, thanks to you!

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