I haven't received but one in the last couple of days, but it was strange:
 
LISTSERV 4296 A PUN 00000244 001 USER 06/18 20:48:29 UNNAMED   FILE     3
 
The file was receivied with (none) (none) as the name at some point, I guess.
That's a new twist to it, though probably not useful information.
 
--Shane