What is a Winmail.dat File and How to Open it?

Most people who have ever received a winmail.dat email attachment file will have two questions coming to their mind. That’s what it is and how to open it. This tech-recipe will answer your questions in details and share the knowledge and tips of Winmail.dat files with you guys.

What is a Winmail.dat File?

Non-Outlook users may have revived an e-mail arrived with a winmail.dat attachment. That’s because the email was send by an outlook user and he used Rich Text format (RTF). Unlike plain-text formatting, this Rich Text Format can display different text styles, fonts, colors and other specialized attributes within a message. An e-mail containing a winmail.dat file looks like an empty e-mail with only one attachment. But it is the winmail.dat file that packs the original e-mail information like subject, body and attachments in. In some cases, it may also appear with a generic name like information01.dat. These attachments are sometimes called T.N.E.F. (Transport Neutral Encapsulation Format) files, which is the technical term for the format Outlook uses. Broadly stated, if a sender (Windows user) send a rich text email via a Microsoft email application (such as Outlook, Outlook Express or Exchange), then non-outlook recipient (both Mac and Win users) will receive a winmail.dat attachment in the email.

If you want to avoid receiving these irksome attachments in the future, you should ask the sender not to edit email in Microsoft Rich Text format but in the plain-text format.

How to Open a Winmail Attachment?

For Win users, Winmail Reader is a useful and simple tool to read, convert, and save Winmail attachments. It is a freeware application that works on the later versions of the Windows operating system including XP, Vista, and Windows 7.


winmail reader for win


For Mac users, Enolsoft Winmail Viewer for Mac is the best choice. With it, Mac users can quickly open and browse the files contained in the winmail.dat attachment, as well as extract and save the files on Mac OS X 10.6 and higher. Click here to learn the tutorial of how to use Enolsoft Winmail Viewer for Mac.

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Try all the features of Enolsoft Wimail Viewer for Mac

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  • Quickly browse attachment of a winmail.dat (TNEF encoded) file.
  • Open single attachment file with external appropriate applications.
  • Extract and save files contained in the Winmail.dat attachment.
  • Practical, simple, and fast to use.

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