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I have a set of winmail.dat files that apparently have evolved from a set of emails with corrupted headers. It looks like Exchange 2010 changed the headers around sometime last September and basically rendered exported .eml files unable to open. Now the HTML/PlainText emails seem to do ok, but the files that use RichText (specifically Microsoft's TNEF format) will not open in any program, Microsoft or not.

I've attempted to use many different non-Microsoft converters and they see it as a corrupted message as well.

If I remove the headers of the email, rename it as a winmail.dat file, some emails will open in Word, but most won't.

If you take a look at the email in a text editor, there are null characters EVERYWHERE that distort the email itself.

Anybody have any experience with this and/or suggestions on how to at least open it?

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You can try using to view the files. I have had some success with it previously. – Oliver G Jun 12 '12 at 13:58
Yeah, that was another thing I tried as well. It just lets me download the winmail.dat file again, but doesn't do any conversions unfortunately. Good suggestion though. – tearman Jun 12 '12 at 14:34
Have you tried this? – Oliver G Jun 12 '12 at 14:36
Yes, that one too. – tearman Jun 12 '12 at 14:56

Try using Thunderbird to import data. It has a decent filter that can recover most of the mail from Outlook folders.

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I've actually already tried this one as well, using Mozilla's LookOut plugin. – tearman Jun 12 '12 at 22:09
up vote 0 down vote accepted

I figured out that if you open the file in a text editor, then look for the "html" tags, copy all of that between the tags to another text file, then rename it as a .doc file, Word should be able to open it.

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