Issue: When trying to migrate the mailboxes in Exchange, throws the below Error
Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=MAILBOX01/cn=Microsoft System Attendant
Resolution:
Ideally it happens if there is no proper Database Home MDB mapped for Microsoft System Attendant mailbox for the server.
In the ADSIEDIT, Locate the following path, CN=Configuration,CN=Services,CN=Microsoft Exchange,CN=,CN=Administrative Groups,CN=Exchange Administrative Group (FYDIBOHF23SPDLT) ,CN=Servers,CN=,CN=Microsoft System Attendant – Home MDB
and map the correct available Database and restart IIS Server using IISREST /NOFORCE.
After service restarted, check the service health and try to move the mailboxes. Belive it will work.