Project Server or WSS. Do you not receive e-mails regarding your schedule (
if so you will need to check if the exchange server address has changed) or
dont you receive emials about risks and issues ( if so you will need to check
if Windows Sharepoint Services e-mail notificaiton is turned on).
since you sayed that it worked previously, I would assume that something has
changed in your Exchange Server environment.
I hope this put you into the right direction