To mount a mailbox database:
In the left pane of the ESI window, select Applications > Exchange and the applicable mailbox forest.
In the center pane, click Mailbox Databases, and then select the database to mount.
In the Actions pane, click Mount Mailbox Database.
In the Mount Mailbox Database page, confirm that the correct database is listed, and then click Next.
In the Review Input Parameters page, review the settings, and then click Next to confirm them.
In the Progress page, click Next.
Note: Click More Information for more progress details. If a problem occurs, an error message appears along with options to resume or roll back the process. After the error is resolved, click Resume to resume the process. Click Rollback to revert to the previously executed step.
In the Summary page, click Finish.