What's that winmail.dat?

Reader Richard Shaffer is perplexed by the contents of his email. He writes:

Some email messages I receive contain “winmail.dat” attachments. I can’t open these with any applications I own. Any suggestions?

Yes. Copy the following text into a reply to anyone who sends you a message that contains such an attachment:

Dear User of Microsoft Outlook,

Thank you so much for taking the time to write. Regrettably, I’m unable to view the formatting you so carefully applied to your message because — and I know this may come as a shock — many, many people in the world do not use Microsoft’s Outlook. Let me explain.

When you apply Outlook’s Rich Text format to your email messages, only those recipients who open them in Outlook can see that formatting. The rest of us — and believe me, our numbers are significant — see the message along with a winmail.dat attachment that we can not open. The problem can be compounded when any other attachment you included with the message is combined with this winmail.dat attachment. So, for example, any pictures you’ve sent of the family’s new iguana will go unseen.

To address this issue, please send future messages as plain text. (If you need help learning how to do this, see this Microsoft support document.) While I’m certain some of those you correspond with will miss the many fonts, underscores, shadow effects, and italic passages it is within your power to apply to your messages, I’m sure they’ll understand that you provide a greater service by sending messages that can be read by all recipients rather than just those who’ve adopted Microsoft’s email client.

Thank you for your consideration.

Update: A couple of readers have suggested Josh Jacob’s TNEF’s Enough, a free utility for extracting readable data from these winmail.dat files. Worth a shot if your Windows using pals won’t be taught.

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