Yes, ITS filters all mail that comes in through the U-M e-mail gateway machines for viruses. Outgoing mail is also checked for viruses. For details about how this works, see the E-Mail Virus Filtering at U-M page.
Note that other campus e-mail providers may do their own virus filtering.
Yes, even though U-M blocks viruses at the mail gateway, you still need antivirus software on your machine—and it needs to be configured for automatic updates.
Not all viruses spread through e-mail. You need to protect your machine from viruses that attack by other means.
When a new virus is discovered, there will be a delay between the virus discovery and the release of new filters. You increase your chances of protection during this time by having antivirus software on your machine.
If you use multiple e-mail accounts, you need to make sure you are protected from virus-infected mail sent to any of those accounts.
Better doubly safe than sorry.
See Safe Computing for information about downloading and installing antivirus software. U-M provides:
Microsoft Security Essentials or Forefront for Windows
Sophos Anti-Virus for Macintosh
This happens when your e-mail address is put in the sender field of a message sent by someone (or something) else, and that message is rejected as undeliverable. In short, here is what happens:
Mail is sent that appears to be from you, but is not. (A virus might raid a victim's address book for addresses and find yours, or a spammer might use addresses harvested from websites or elsewhere, or a program randomly generating addresses might generate yours.)
The mail is delivered to an invalid address. Or the mail is delivered to a valid address but is rejected because it contains a virus.
The destination mail system returns the mail to the apparent sender (you).
There isn't much you can do about these rejections other than report the problem to the ISP where the mail actually originated. Sometimes you can determine this from looking at the full headers. If a virus rejection message's full headers indicate it originated at U-M, you can forward it to the ITS Service Center (firstname.lastname@example.org) for assistance.