Ok, I'm having this same problem. It appears to be a problem with the way Versamail is attaching images. I run my own mail server so I can check the logs, and this is what I find:
qmail-scanner[71272]: Policy:Bad_MIME_Break:RC:0(70.217.140.41):SA:0(?/?): 117.1574 418542
user@domain.com user@domain2.com Fwd:_Pic
and more logs...
Sat, 05 Aug 2006 16:33:18 EST
from@domain.com to@domain.com Pic Disallowed breakage found in header name - potential virus clamdscan: 0.88.1/1416. spamassassin: 3.1.1. perlscan: 1.25-st-qms.
Other email clients probably work just fine. Maybe its time to get into contact with Versamail...
NovceGuru