XADM: How to Prevent Logons During Move Mailbox

This article explains how to move mailboxes between two Exchange Server computers in the same site while preventing users from logging on. This is useful in situations where you are approaching a disk space limit or a 16-GB database limit in Exchange Server versions 4.x and 5.x.

To restrict logons to the information store and still allow a move mailbox operation to complete, follow these steps:

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

1. Stop the Information Store Service on the Exchange Server computer.
2. Run Registry Editor (Regedt32.exe).
3. From the HKEY_LOCAL_MACHINE subtree, go to the following key:
   \SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
4. On the Edit menu, click Add Value, and type Logon Only As in the Value Name text box. Type REG_MULTI_SZ in the Data Type text box.
5. Click OK. In the Data text box, type the entire Distinguished Name of both the System Attendant mailbox and the Directory Service mailbox of both the source and target servers on separate lines and then click OK. For example:

   /o=OrgName/ou=Site1/cn=Configuration/cn=Servers/cn=Server1/cn=Microsoft System Attendant
   /o=OrgName/ou=Site1/cn=Configuration/cn=Servers/cn=Server2/cn=Microsoft System Attendant
   /o=OrgName/ou=Site1/cn=Configuration/cn=Servers/cn=Server1/cn=Microsoft DSA
   /o=OrgName/ou=Site1/cn=Configuration/cn=Servers/cn=Server2/cn=Microsoft DSA
   						

   NOTE: To find out the Distinguished Name of the mailbox that you would like to add, you may need to start the Exchange Administrator program in raw mode. To do so, at a command prompt, type c:\exchsrvr\bin\admin.exe /R, where c: is the drive where the admin.exe file is installed.
   
   In raw mode, select the mailbox that you wish to allow to log on, and on the File menu, click Raw Properties. In this case, choose the System Attendant mailbox and the Directory Service mailbox. You can see the raw properties of these two mailboxes from Mailbox Resources. Next, look for the Object attribute that says Obj-Dist-Name; this is the entry that goes into the registry as mentioned in step 5. You may need to scroll to get the full path.
6. Click OK.
7. Close the Registry Editor.
8. You will need to restart the Information Store service in order for the change to be activated.
   
   This entry will only allow the mailboxes that have permission to log on, in this case, the System Attendant and Directory mailboxes. Leaving the Logon Only As value blank will prevent everyone from logging on.
   
   In order to allow all users to log on again, you must stop the Information Store service, then delete the Logon Only As value from the registry, and restart the Information Store service.