Email attachments are by far the most common cause of infection. ITS tries to block all potential virus attachments from ever getting to your email box, but occasionally a new one slips through before the virus recognition software can be updated to recognize it. You have probably seen one of the notices that an email attachment has been removed or archived before the email was delivered.

Many newer viruses "spoof" the return email address so it appears to come from someone you know, but it really doesn't. When one of these viruses infects a computer, it sends a copy of itself to every email address it finds on the machine and randomly uses other email addresses in the sender field. You cannot reliably know who actually sent you an email anymore.

Note that you can preview many attachments by clicking your right mouse button on an attachment and selecting View. The GroupWise viewer does not open (and therefore does not run) the attachment, so you can safely look at the content of Word, Excel and other people-readable attachments to see if they are legitimate.