I resolved a problem for a client earlier on where their emails were sitting in the Outbox of Outlook. I did the usual troubleshooting - checked Exchange services etc which were all ok; but when I went into System Manager I noticed that the mailbox store was dismounted. I remounted it and everything has been fine since. They are running Exchange 2003 under SBS 2003. What sort of problems can cause a mailbox store to become dismounted?

There will be some entries in the event logs when the store is dismounted. What do they say?

Hi there, Please go through the application event log.. you will get more information about it.. Kottees : My Blog : Please mark it as an answer if it really helps you.

I did look in there, this was the only error: Event Type: Error Event Source: MSExchangeSA Event Category: MAPI Session Event ID: 9175 User: N/A Computer: <var>Computer_name</var> Description: The MAPI call 'OpenMsgStore' failed with the following error: The Microsoft Exchange Server computer is not available. Either there are network problems or the Microsoft Exchange Server computer is down for maintenance. The MAPI provider failed. Microsoft Exchange Server Information Store

I did look in there, this was the only error: Event Type: Error Event Source: MSExchangeSA Event Category: MAPI Session Event ID: 9175 User: N/A Computer: <var>Computer_name</var> Description: The MAPI call 'OpenMsgStore' failed with the following error: The Microsoft Exchange Server computer is not available. Either there are network problems or the Microsoft Exchange Server computer is down for maintenance. The MAPI provider failed. Microsoft Exchange Server Information Store Ok, that is just a result of the store not being avail, not the cause. that's it? Nothing more? Is this the first time this has happened? Any 3rd party software installed? ( A/V , anti-spam, etc...) I would also download and run ExBpa against the server for health and permissions check.

I thought that. No other information though. This is the first time that it's occurred so I will monitor going forwards.

Another possibility is that someone dismounted it manually. Human intervention can explain a lot! :)

I doubt it - they're not the sort of client to click on things randomly.

Ok, well I would defintely run ExBpa against the server and also check disk space and verify you arent pushing against any limit for the store or logs. Also verify that you arent hitting the store max - which can be set as high as 75GB in Exchange 2003 SP2; http://support.microsoft.com/kb/912375

Will do. I verified the limits earlier on - for instance the main database is only 19GB. Thanks again.

On Mon, 26 Mar 2012 12:28:22 +0000, A_D_ wrote: >Another possibility is that someone dismounted it manually. Human intervention can explain a lot! :) Boy, I wish I could say that! I've had every database on a server dismount and not one trace of a failure in the application or system log. I've had that happen twice in the last four years. Hilarity generally ensues during the "root cause analysis" phase of typical "punish the innocent" aftermath. :-( --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP