[multiple threads on the same topic combined. Thus, this thread may read a little odd.]
Winmail.dat is not a virus. It is file is used to preserve/delineate rich text formatting. It can be automatically added when emailing a zip file or text containing an RTF file, etc. It is not harmful.
I just downloaded the driver and scanned it with a couple of virus detection programs. Everything checks out OK.
Have any of you having problems recently updated to Windows 10? The Windows 10 version pushed by Microsoft has led to a few problems for some, particularly with Outlook, and this issue may be related.