Exchange users would notice no new email in their accounts, and senders would receive a notice that their message was temporarily deferred. Mail delivery is only deferred; it should be correctly delivered once the issue is resolved.
UPDATE
[2010-10-11 10:24:57 | Lars Rohrbach]
As of about 10 a.m., new mail messages should be delivered to EECS Exchange accounts on FONTUS, after being processed by BWRC’s newer Ironport anti-spam appliance.
We are continuing to work on the delivery of email that has accumulated since Saturday night.
UPDATE
[2010-10-11 12:40:43 | Lars Rohrbach]
Mail service to the EECS Exchange server FONTUS is back to normal. New mail since 10 a.m. this morning has been delivered appropriately, and the mail that accumulated since Saturday night has slowly been processed over the past couple of hours. All deferred mail has now been delivered.
All mail for FONTUS is now going through a newer BWRC Ironport anti-spam appliance. The deferred email problem was due to the transition from the old (no longer supported) Ironport hardware to the new Ironport hardware.
Resolved as of 2010-10-11 12:30:00