I have always thought, smugly, that by using Gnus I was insulating
myself from viruses.  However, when I looked at the enclosed email
under NTEmacs, I got a dialog box saying that no known program could
open mm.304-VK (actually, the characters after "mm." vary each time I
look at the email).  This seems like it's a few bytes away from being
able to run arbitrary programs.  

Any clues what might be going on here?