Today I was wondering what if the System Attendant mailbox goes missing, how will the server be impacted so thought I might as well write a post on that so here goes.
>>When does the System Attendant mailbox get created? Can it be moved or re-created?
The System Attendant mailbox is created when the system attendant is created on a server. It is associated with the first mailbox store created on a server.
If an attempt is made to delete the mailbox store containing the System Attendant mailbox, the following warning will appear:
Deleting this mailbox store may result in the loss of system messages used by Exchange, such as Free/Busy or Key Management Security. If you choose to continue, you need to restart the system attendant service after the store is deleted.
If the store is then deleted, the System Attendant mailbox will be moved automatically into another mailbox store on the server, that is, the HomeMDB value on the directory object will be updated. The system attendant service must be restarted to reconfigure MSExchangeFBPublish to use the new mailbox location, and the mailbox object may not reappear under the Mailboxes node of Exchange System Manager until it is used in the future.
If there is a System Attendant directory object but no mailbox object, the mailbox store object will be re-created automatically in the mailbox store referenced by the HomeMDB attribute as soon as it is needed. Note that one cause of this is using a blank store for troubleshooting
If there is no System Attendant mailbox available on a server, and in a mounted and functional mailbox store, anything that requires it will fail. You will see Event 9175 logged in the Application log, indicating a failure to log on to this mailbox by the system. You will see Outlook Web Access generated free/busy information not getting updated. You will see mailbox moves fail. It is an important mailbox to have configured properly and available.
Hope this helps