Can you reach the Exchange server via OWA?

Can you ping the server by name and IP address?

Check the Exchange server. Ensure all Exchange services that should be running are running.

Check your store size. Has it exceeded its limit–store will not mount if it has.If you have not edited the registry to allow a store larger than 16GB, now would be a good time. It can be increased to 75GB.

Have you run oout of disk space on the drive hosting the store, hosting the logs. If the logs go back forever, or even a few days, you need to do a full backup of Exchange with an Exchange aware backup program so the logs can be written tothe store and deleted. Then ensure that this is done every day.

Check the event logs on the server. Follow up and resolve any errors found. Again, use http://www.eventid.net to assist.

If you have no idea what any of these steps involve, call someone to come in to resolve your problem for you.You have now been without e-mail for 4 days. Most places where I work would find 4 hours to be unacceptable. Wow, I just looked back at your post, and it is dated February 11, 2008. Sure hope your problem has been resolved.

I’d check Exchange Server application logs first.