Let me start by saying that I'm kind of a newcomer to servers and Exchange. The IT manager at the company I work at resigned so it has left me (The helpdesk guy) as the network admin as well. Ok here's my problem. Almost every night our Exchange server email system "goes down" as in noone can get mail and outlook says the connection has been lost. When I invetigated this further I found that in Exchange system manager the mailbox store is red and appears to be dismounted....if you right click it and select to mount it it mounts fine and the email system comes back up. Ok so my question is why would this be happening and how can I prevent it. This is happening 3-4 days a week and is causing me to rush in at early hours. This machine runs Exchange server 2003 and Veritas backup exec. Our backups run over night and I was starting to think that may have been the cause until I looked in event viewer and say the error that I am going to include in a screen shot. It appears that the mailbox store database may be too big? Can anyone please offer some tips to an overworked newcomer on how te resolve this? Thanks!