Moving System Attendant Mailbox

To move the System Attendant mailbox:

1.  Change the homeMDB attribute of the Microsoft System Attendant object for the server to reflect the new database. For example, if the homeMDB value is
CN=Mailbox Store (SERVER1),CN=First Storage Group,CN=InformationStore,CN=SERVER1,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=First Organization,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=mycompany,DC=com
and you want to move the System Attendant mailbox to a database called DB2 in storage group Second,

change the homeMDB value to

CN=DB2,CN=Second,CN=InformationStore,CN=SERVER1,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=First Organization,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=mycompany,DC=com

The System Attendant object for each Exchange server is located in the Configuration container of your Active Directory forest. The path to it is:
CN=Microsoft System Attendant,CN=[server name],CN=Servers,CN=[administrative group name],CN=Administrative Groups,CN=[organization name],CN=Microsoft Exchange,CN=Services,CN=Configuration

Note:  There are several ways to edit the homeMDB value. You can use the Adsiedit tool, the LDP tool, or the LDIFDE tool. 

2.  Stop and restart all Exchange services. 

3.  Run the Mailbox Cleanup Agent against the original database. To access the Cleanup Agent, right-click the Mailboxes object for the database. After you run the Cleanup Agent, the original System Attendant mailbox should have a red X next to it, indicating that it is no longer connected to an Active Directory object. 

4.  Right-click the disconnected System Attendant mailbox, and then permanently delete the mailbox.

Warning After you complete this step, you cannot move the mailbox back to the original database. To move it back, you must delete the physical database files, and allow a fresh database to be re-created

5.  From a client workstation, send a mail message to the System Attendant mailbox, requesting a delivery receipt. Address the message in the following format, including use of the square brackets:

6.  Monitor the Application Log carefully for errors relating to the System Attendant mailbox.