A simple explanation of email virus scanning may help. Most email virus scanners work as a proxy, intercepting incoming mail via a TCP port internal to the computer (localhost), scanning it and passing it on the email client if it is not caught as a virus. So they attempt to catch it while being downloaded to your client. The standard scanner instead checks the email when you try to open it after it hits the email client. Most (all?) AVs do this again anyway, even if you already have done the email scan, so somewhat redundant. Don't know what CAVS does if you just download your mail to your client and don't read it yet-but if there is no way to open it, won't do any damage until you do try. I like to know ASAP, so use an email scanner (Avast!).