Gmail automatically scans every attachment when it's delivered to you, each time you open a message, and attachments you send to check for viruses. This helps to protect everyone who uses Gmail, and prevents the spread of viruses.
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 the attachment 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.
http://support.google.com/mail/bin/answer.py?hl=en&answer=25760
ITS Tip: There are two ways to protect your email.
Google@UH users: Refer to the instructions at Ask Us 1208.