I hit the "quicklook" option for the attachment and it said it was a HPIP video file (whatever that is) and I didn't think that was right. I tried to open it in TextEdit and it appeared to be a Word Document as I saw some text and a bunch of garbage that was probably images and/ or formatting.
I then changed the file extension from ".dat" to ".doc" but the file would not open. I then tried to change it to ".pdf" and it opened in Preview and it was a pdf file for the manual for our GPS, but I didn't see the phrases that I original saw when looking at the file as text.... hmmmmmm.
Bob did a quick Google search "open winmail.dat with mac" and he found this handy little FREE application, TNEF's Enough.
Here's their explanation of why we Mac Users get these files:
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."Interesting...
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.
I then saved the attachment to my desktop and then Opened With TNEF.app which gave me two files, a Word Document and the pdf manual. I might still be missing something but I wrote to Humminbird and told them my problem. Hopefully they'll not just re-send the same message, but actually attach the individual documents properly to the email.
There is a similar application, called tnefdd, also FREE on SourceForge.net I just downloaded this app and tried it on the same file and received the same results.
--> Here's something else that works !!!
I just forwarded this document in question to one of my Gmail email accounts, and the attachments were there just perfectly... no attachment called winmail.dat, but the two files with their proper filenames.
Hope this will help someone.