Received a winmail.dat attachment and can't open it? Drop it here — MailSnap decodes it instantly and extracts everything inside.
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The sender uses Microsoft Outlook configured to send email in Rich Text Format (RTF). When Outlook sends RTF emails, it wraps the content and attachments in a TNEF (Transport Neutral Encapsulation Format) container called winmail.dat.
Only Microsoft email clients can decode TNEF natively. If you use Apple Mail, Gmail, Thunderbird, or almost any non-Microsoft client, you'll see winmail.dat instead of the actual content.
How do I open a winmail.dat file?
Drop it onto MailSnap. It decodes TNEF in your browser and extracts the email body and all attachments.
What program opens winmail.dat?
MailSnap opens it in your browser — nothing to install. On Mac, Letter Opener and TNEF's Enough also work. On Windows, Outlook opens them natively.
Is winmail.dat a virus?
No. Winmail.dat is a legitimate Microsoft file format. That said, like any attachment, its contents could theoretically contain malicious files — always download attachments only from trusted senders.
Can I open winmail.dat on iPhone or Android?
MailSnap works in mobile browsers too. Open mail-snap.com in Safari or Chrome on your phone and tap to select the winmail.dat file.