All databases have internal structures that require some degree of maintenance to ensure logical consistency, and Exchange is no different. You can take a database offline to rebuild it with the ESEUTIL utility, but a database rebuild requires you to deprive users of access to their mailboxes. Microsoft designed Exchange to be highly available with as little downtime as possible, and online maintenance is necessary to keep the databases in good order while allowing users to continue working.
The maintenance Exchange performs can be grouped into the following categories:
Miscellaneous content maintenance. These tasks are performed during the maintenance schedule assigned as a property of mailbox databases, typically from 1 ...