If you use the View Usage report generated byu SBS2003, you may notice that one or more users will show up with an unusually high number of outgoing mail. Your first reaction may be: Is my server being used as a relay? Or have I been hacked?
But don’t worry — it’s just a flaw in the way it counts outgoing mail IF you send an email to multiple different email domains.Unfortunately there’s not a fix for it right now. Read more at KB 867457!
http://support.microsoft.com/default.aspx?scid=kb;en-us;867457