Restoring Exchange 2000/2003 mailboxes with ExMerge after moving the mailbox to Exchange 2007

Daniel Petri

Jan 8, 2009

Imagine the following scenario:

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You perform a full backup of mailbox store on Exchange 2000/2003.
You move a mailbox from the backed-up store to an Exchange 2007 server.
You try to leverage the Recovery Storage Group feature on the Exchange 2000/2003 server to restore the contents of the mailbox in question using ExMerge to restore/export the contents of the mailbox from a date before the mailbox was moved.
The ExMerge export phase fails with the following error in the exmerge.log: Error opening message store (MSEMS). Verify that the Microsoft Exchange Information Store service is running and that you have the correct permissions to log on. (0x8004011d)

Usually you would get this error if the account you run Exmerge with does not have full permissions on the mailbox you are trying to restore, but this case is a bit different. Even if you grant yourself Full Mailbox Access and get rid of the “Send As” and “Receive As” denies (see KB322312 for details), the process still fails with the error message above.

The issue stems from the fact that the mailbox in question has been moved to a different mailbox store from the one it was backed-up from. In order to better understand the problem, lets look at how Recovery Storage Group links a mailbox from RSG to an existing account in AD and what are some of the checks that are performed when you try to export the contents of a mailbox from a database mounted in the RSG:

msExchMailboxGUID attribute: this is the first test that is being performed. The GUID of the mailbox in the RSG (taken from the database itself in the RSG) must correspond to an existing account in the AD. If Exmerge can not find the GUID of the mailbox you are trying to restore in the AD, it will fail.
msExchOrigMDB attribute: When a database is added to RSG, its msExchOrigMDB attribute is populated with a distinguished name that points to the original database that was backed-up. When Exmerge runs, it checks whether the mailbox we are trying to restore/export exists in the the database the msExchOrigMDB points to. If the mailbox store does not exist or the mailbox has been moved to a different store, the test fails and the following message is logged in the exmerge.log file: “Error opening message store (MSEMS). Verify that the Microsoft Exchange Information Store service is running and that you have the correct permissions to log on. (0x8004011d)”

Restoring Exchange Mailboxes

Obtain the distinguished name of the store where the mailbox currently resides. There are numerous ways of locating the DN of the database. Here are 2 examples: Using command line (I find it quickest): query the homeMDB attribute of the user’s account whose mailbox we are restoring using dsquery:
```
C:'>dsquery * -filter "samaccountname=guyt" -attr homemdb
```
Query result:
```
homemdb
CN=Mailbox Store (E2K7MBX01),CN=First Storage Group,CN=InformationStore, CN=E2K7MBX01, CN=Servers,CN=Exchange Administrative Group (FYDIBOHF23SPDLT), CN=Administrative Groups, CN=ExchOrgName,CN=Microsoft Exchange,CN=Services, CN=Configuration,DC=company,DC=corp
```
Using adsiedit.msc: Navigate to the user account whose mailbox you are restoring and copy the value of the homeMDB attribute of the user account:

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1. Drill down in the Domain partition to locate the account in question:
2. Right-click the user account and select “Properties”. Locate “homeMDB” attribute and click “Edit”:
3. Copy the value of the homeMDB attribute which would look something like:
```
CN=Mailbox Store (E2K7MBX01),CN=First Storage Group,CN=InformationStore, CN=E2K7MBX01,CN=Servers, CN=Exchange Administrative Group (FYDIBOHF23SPDLT),CN=Administrative Groups, CN=, CN=Microsoft Exchange,CN=Services,CN=Configuration, DC=company,DC=corp
```
Edit the msExchOrigMDB attribute of the object representing the restored database in the Recovery Storage Group
1. Open adsiedit.msc and locate the object representing the database you have recovered to the RSG. It will be somewhere under:
```
CN=Mailbox Store (E2K3SRV01),CN=Recovery Storage Group,CN=InformationStore,CN=E2K3SRV01,CN=Servers,CN=first administrative group,CN=Administrative Groups,CN=,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=company,DC=corp
```
2. Right-click the mailbox store object and select “Properties”. Locate the msExchOrigMDB attribute and click “Edit”
3. Replace the current value with the distinguished name you obtained in Step 1
4. Click OK and wait a bit till the change replicates to other DCs in your environment.
5. Restart the “Microsoft Exchange Information Store” service on the Exchange server hosting the Recovery Storage Group.
Mount the database in the Recovery Storage Group
Run Exmerge. This time you should be able to export the contents of the moved mailbox.

Warning: After you follow the instructions above you, you will not be able to use Exmerge to access any mailboxes that you did not move to a different mailbox store. If you want to access the mailboxes that remain in the original mailbox store, you must change the msExchOrigMDB attribute back to its original value.

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