Error: Failed to process MAPI. dbo.MailBoxSelectByLegacyDN returned more than one result (4306885)

The Data Loader Service fails for the Journalling MAPI dataloader and returns the error "Failed to process MAPI, with the exception message of dbo.MailBoxSelectByLegacyDN returned more than one result."

The cause of this error can be attributed to  two users in the Archive Manager SQL database showing   the same LegacyExchangeDN associated with their login account.   This can happen in situations where a user was associated with a specific mailbox, had the legacyexchangeDN associated with its user account, and then removed and added a different user account to the same mailbox which in turn would stamp the legacyexchange DN on that account as well.   When the Active Directory Connector is run   it would pick up the logins and this would result with two accounts having the same legacyexchangeDN in the database.   This would have been updated in Active Directory as validated with MFCMAPI and LDP, however this information is retained in the database.

If one of these accounts are being used   with the Data loader service, when it tries to run, it will detect that there  is more than one account with the unique legacyexchangeDN and will stop functioning as it does not know which account to choose.

If this takes place in your environment,   please perform the following steps.

1.   Locate the duplicate user accounts in the SQL database that have the same legacy exchange DN.   This can be accomplished by  executing  a query on the login table in SQL.   The following query would be appropriate:

select * from login where ActiveDirectoryExchangeLegacyDN = 'insert legacyexchangeDN here'

2.   Once you have found the duplicates, determine which account should currently have the   legacyexchangeDN attribute associated with its account.

3.   Open the Login table in SQL Server Management Studio.   Locate the duplicate account or accounts  that have the incorrect legacy exchangeDN.    Clear the field that is  populated in the ActiveDirectoryExchangeLegacyDN column.

3.   Open the  Mailbox table in SQL Server Management Studio.   Locate the duplicate account or accounts  that have the incorrect legacy exchangeDN.    Clear the field that is  populated in the ActiveDirectoryExchangeLegacyDN column.

Once this has been completed there should only be one reference to the legacyexchangeDN which should remove the error and resolve the issue..

An example of why this may be  happening in your environment   can be that the journalling account was removed from the Journalling mailbox. Then a new user who never had a mailbox, connected to the journalling mailbox within Exchange which makes that mailbox associate with the user. When that takes place the legacy Exchange DN of the mailbox gets applied to the user account that connects to it. The directory connector was then run and this resulted in the already journalling account and the new user account having the same legacy ExchangeDN in the database.