Answer
There was a problem in 3037 whereby the scanner was called whether or not content filtering and/or virus scanning was enabled.
This has now been fixed and an attachment will only be scanned if a valid GMS Anti-Spam key is present and restricted word scanning is enabled or reject attachment extensions is enabled or if a valid GMS Anti-Virus key is present and the virus scanner is activated.
Keywords:SMTP resources usage CPU attachments scanning ntmvscan.dll