All of a sudden, e-mail notifications are no longer working in SDP.
I check the log and it just says...

System Log Message       :       Exception while trying to send notification for the request.
Module     :     Helpdesk
Sub Module     :     -
Type     :     Error
Action     :    
Occurred At     :     Aug 26, 2009 11:10 AM
Probable Cause     :     -
Performed By     :     USERNAME


Any ideas about what may have happened?