There is a new virus going around that clamav does not have a signature for yet and thus is not catching. Our spam filtering software does recognize it as spam and is putting it in your spam folder. If you find e-mail in your spam folder with an attachment, I strongly recommend against opening it as it most likely contains a virus.
The volume of this virus is so large that it has overloaded our incoming mail servers and caused mail to be backed up in queue. I was able to make some adjustments that improved the mail servers ability to process mail and it is catching up, but as of 2AM it has worked through about half the queue, so at this rate it will probably be caught up by around 5AM.
Hopefully the clamav folks will kick out a database that includes a signature for this thing and put an end to it, but to prevent your machine from being infected, do not open any attachments you are not expecting and keep your anti-virus database up to date.