Antigen found Win32.Mydoom.O worm

Antigen for Exchange found instruction.scr infected with Win32.Mydoom.O worm.
The message is currently Purged.  The message, "Returned mail: see transcript 
for details", was
sent from wormbase@xxxxxxxxxxxx and was discovered in SMTP Messages\Inbound And 
Outbound
located at NFPA/HQ/NFPA_NT1.