Have you received a an email that contains the words "possible virus" in the header? If so, be cautious about opening the message. Be even more cautious about opening its attachment. Unless you're certain the email attachment is legitimate (it's sent from a trusted source, you're expecting it, the message carrying the attachment doesn't look suspicious, etc. ), you should refrain from opening it. If you have any doubts, simply delete the message.
Why? During Fall Quarter 2004, Stanford expanded its anti-virus system by giving it the ability to alert people to the fact that their email messages "might" be carrying an attachment infected by a virus. It does this in several ways.
First, email gets a "possible virus" flag when the anti-virus system cannot scan the email's attachment. This happens, sometimes, because the attachment is a compressed file (which can't be opened for scanning), or because, though the attachment has a virus, the filter for detecting the virus is not yet available on the anti-virus system. No matter the cause, the system always decides to err on the side of safety.
Second, the anti-virus system takes a look at an attachment's file extension name. Extensions like .pif, .lnk or .bat will usually get tagged. The sad fact is that many, if not most, file extensions are seldom associated with legitimate attachments. The obvious exceptions are ".zip" attachments. Lots of perfectly good attachments are "zip" files. Unfortunately, because files ending with "zip" are compressed, the anti-virus system can't peer inside them. These files could contain almost anything...including a virus. The anti-virus system therefore flags them as possible viruses.
Regardless of how it happens, or how often, the caveat remains the same: if you get email tagged "Possible virus", check the source and be careful about opening the attachment. The last thing you want is to infect your computer, and maybe your friends' computers.
More information about virus filtering can be found at:
http://www.stanford.edu/services/email/virus.html
If you have any questions about viruses on your computer, please submit a HelpSU request at:
