Anti-virus scanning attachments
Attachments in Gmail messages you send and receive are automatically scanned for viruses.
What happens when viruses are found
If an attachment you're trying to attach is infected with a virus, you'll see a "Virus detected!" error message. You'll see the option to send the email without the attachment.
When Gmail finds a known virus attached to an email that's been sent to you, Gmail will reject the message and let the sender know.
If Gmail finds a virus in an attachment on an email that's already in your inbox, you won't be able to download the attachment.
"Oops...the virus scanner has a problem right now" error
If Gmail can't scan certain files at the moment, you might see the "Oops...the virus scanner has a problem right now" error.
If you see this, you can try downloading the attachment later, or you can open the attachment at your own risk.