I recently got an email in hotmail with a winmail.dat attachment. The email text included a pdf file, but there was not another file attached. After some digging this is what I found…
When an email is written using Outlook in the rtf format it can be received by other email programs as the text and an attachment called winmail.dat. That winmail file can contain pictures, attachments, fonts, etc. from the rtf formatting. To open the file you need another program that will unpack everything in the file. I downloaded WinMail Decoder 2.0 on trial and dropped the file onto WinMailDecoder.exe that comes in the zip file. If unpacked everything and voila I have my pdf file.