Make sure that the Anti-Virus Exclusion lists are enabled on ePO enterprise server level (Antivirus Management level) as per the recommended Microsoft article-
Directory Exclusion lists for Exchange (exchange 2007)
PickupDirectoryPath:
C:\Program Files\Microsoft\Exchange Server\TransportRoles\Pickup
ReplayDirectoryPath:
C:\Program Files\Microsoft\Exchange Server\TransportRoles\Replay
RootDropDirectoryPath:
C:\Program Files\Microsoft\Exchange Server\TransportRoles\data\Queue
C:\Program Files\Microsoft\Exchange Server\TransportRoles\data\IpFilter
C:\Program Files\Microsoft\Exchange Server\Working\OleConverter
C:\WINDOWS\system32\inetsrv
C:\Program Files\Microsoft\Exchange Server\ClientAccess
Process Exclusions and File Name Extension Exclusions
Refer Microsoft recommended Article at: http://technet.microsoft.com/en-us/library/bb332342(EXCHG.80).aspx
Refer managing McAfee Anti-Virus file and folder exclusion at https://kc.mcafee.com/corporate/index?page=content&id=KB50998&pmv=print