We have enabled the F9 antivirus scanning for our account but I think that it might not operate because we have also opted to set "mail to this domain to be delivered to my static IP by SMTP".
Am I correct in this assumption ?
p.s. The reason that I think this is because lots of viruses infected attachments are reaching our mail server.
Yeah, the virus scanning is only carried out once the email reaches our mail servers, so if you have it configured to pass the messages straight through to your own server the virus system won't see your messages and thus won't be able to scan them.