According to Rumpelstiltskin in this message, GMail is using their own antivirus-solution to scan the messages
http://forum.avast.com/index.php?topic=26654.msg217996#msg217996
And if you want to use avast! to scan the gmail-messages you must use stunnel.
More info from the Gmail-site:
[i]How does anti-virus scanning work?
Gmail automatically scans every attachment when it’s delivered to your account, and again each time you open a message. Attachments you send are also scanned. Checking attachments for viruses protects our users and their information, and prevents the spread of viruses.
- If a virus is found in an attachment you’ve received, our system will attempt to clean the file, so you can still access the information it contains. If the virus can’t be removed from the file, you won’t be able to download it.
If our system is unable to scan certain files, you’ll see an error reading ‘Oops… the virus scanner has a problem right now.’ You’ll have the option to try again later or to download at your own risk. Please note that if Gmail can’t scan the contents of the file, we can’t guarantee that it’s safe to view.
If an attachment you’re trying to send is infected with a virus, Gmail will display an error message to tell you, but it won’t clean the file. To send the message without that attachment, click the link in that error message that says ‘Remove attachment and send.’
If Gmail detects that you’re trying to send an infected attachment, we suggest running your anti-virus software in case your hard drive is infected. If you don’t have anti-virus software, you might consider purchasing/installing one of the popular applications so you can protect your computer and information from viruses. The free Google Pack comes with leading anti-virus and anti-spyware applications – you can find out more at the Google Pack homepage[/I]
