tnef Why am I getting Winmail.dat files on my mac from Windows users? Jodi writes in:

I wasn’t sure who I should contact about this, so i am sending this to you. As of late, word attachments coming from my friend on a Windows XP Machine appear as “winmail.dat” files.
When I try to open these, the text runs about 150pp long, (it’s a 4page doc) and the text looks like this:
?<‡META †[1]0 ?Xt=”‡$.
It shows garbage like that over and over again. Admin Can you help me open them? If I forward the message on to a windows user it is fine! What gives?
Jodi have been dealing with this one for a while and there seems to be no rhyme or reason as to when they appear and when they don’t appear. We investigated the possibility of drag and drop causing it – but that wasn’t it consistently. But we found a utility called TNEF’s Enough for our Mac friends here:
winmaildat Why am I getting Winmail.dat files on my mac from Windows users?
You can simply drag winmail.dat into this application and BAM! There is your data ma’am, can we do anything else for you today?
UPDATE: Fix this on your exchange 2007 server by doing this:

On the exchange server, go to global settings, Internet Message Formats, Default Properties, Advanced tab, for “Exchange Rich-Text Format” select “Never Use”.

This will prevent your Exchangeserver from using Rich-Text Format and creating winmail.dat files.

From TNEF’s website:

TNEF’s Enough allows Macs to read and extract files from Microsoft TNEF stream files. The files are usually received by SMTP based e-mail programs from Microsoft Exchange and Microsoft Outlook users. The SMTP based e-mail program will usually receive either a MIME attachment named “winmail.dat” or a MIME attachment with the type “application/ms-tnef.”

The file is a rich text (or MAPI) message that is sent from Outlook to Exchange. When Exchange sends the message to an outside server it writes the MAPI message as a MIME attachment. The unfortunate side effect of this plan is if the Outlook user has someone in their address book as a person who can receive “Rich Text” then the user will receive the TNEF file whether the user uses Outlook or not.

TNEF’s Enough is a freeware application