Tech – for Everyone

Tech Tips and Tricks & Advice – written in plain English.

How To Open .DAT Attachments

A Reader Asks A Question About Email

Q:Someone sent me an email with a winmail.dat attachment that will not open. How can I see the attachment?”

A: There are many types of .DAT files. The winmail.dat (sometimes “ATT0001.dat”) file is usually created by Outlook, and is used to preserve the format that is included in the sending client’s message — which may not be recognized by the receiving client. In the case of Outlook, the winmail.dat file includes Rich Text Formatting (RTF) instructions.

Sometimes they can be open using Notepad.
• Download (save) the attachment, and then “rename” the file. Change the “.dat” part to “.rtf“.
• Now double-click on the renamed file. It should open in Notepad, or just as good, Wordpad, and though there will be some “computer gibberish” there, you should be able to read the message.

However some DAT files are of a “binary encoding”- type, which simply means that some, if not most, of the file you’re viewing with Notepad (a text editor) won’t be seen. There are some methods that can “extract” the contents of the .DAT file.

For example, you may try an online converter like

Or try opening the attachment in Excel … then try Paint …

Or ask the Sender to resend the email by a different service.. like Gmail. (And send them the following instructions..)
Note: To configure your Outlook to not send people .dat files (and be more popular with your peers) – in all versions of Outlook:

  1. On the “Tools” menu, click “Options”, and then click the “Mail Format” tab.
  2. In the “Send in this message format” list, click “Plain Text” or “HTML”, and then click “OK”.

See also:

Tech News Item: New Mac OS X malware disables Apple’s malware protection

Security researchers from F-Secure have spotted a Mac OS X malware that disables Snow Leopard’s XProtect.plist antivirus signatures updates.Read more..

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Today’s quote:You learn something every day if you pay attention.” ~ Ray LeBlond

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October 19, 2011 Posted by | advice, computers, e-mail, how to, Internet | , , , , , , , | Leave a comment