Cannot open mailbox Microsoft System Attendant

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


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.

2 thoughts on “Cannot open mailbox Microsoft System Attendant”

  1. Hi,
    I am sorry if this is a stupid question, but what do you mean by “map the correct available Database”?
    I have this problem while trying to run a simple PS script from my machine:
    Get-MailboxAutoReplyConfiguration -Identity $user

    When I run the very same command from one of the Exchange servers in my organization — it works perfectly fine.

    Thanks in advance for your help!

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