Migration of Exchange Linked Mailboxes from Ex2010 to Ex2016

Question

In a Resource Forest Scenario, we are migrating from Exchange 2010 in the Resource Forest to Exchange 2016. We are migrating the Linked mailboxes from Ex2010 to Ex2016. For some reason, some mailboxes need access from the Account Forest and from the Resource Forest. For this access we have re-enabled the disabled resource account. On Ex2010, both accounts were able to log into the mailbox. After migration to Ex2016, it is no longer possible to log in with both accounts. The resource forest account gets the following error message:

InnerException: Microsoft.Mapi.MapiExceptionLogonFailed

The MAPI log shows the following:

MoMTException:-2147221231 (rop LogonFailed)
-> [ConnectionFailedTransientException] Cannot open mailbox /o=CONTOSO/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=hans.musterba6.
-> [MapiExceptionLogonFailed] Unable to open message store. (hr=0x80040111 ec=-2147221231)
-> [ServerUnavailableException] Connection must be re-established
-> [SessionDeadException] The primary owner logon has failed. Dropping a connection.
-> [ConnectionFailedTransientException] Cannot open mailbox /o=CONTOSO/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=hans.musterba6.
-> [MapiExceptionLogonFailed] Unable to open message store. (hr=0x80040111 ec=-2147221231)

We need to be able to log in to the mailbox with both accounts. The account from the resource forest and the account from the account forest.

Thanks for any Help!

Kind Regards

Steve

Answer 1

Hi Lou,

we have opened a Microsoft Case on this topic. The feedback here was that access with the account (PA) was never supported and is no longer possible with Exchange versions 2016 and 2019.

Thanks

Regards Steve

Answer 2

Hi @ThomaSTSandbox ,

Really thank you for sharing the details!

I would think this is by-design. You can’t use PA account in Exchange 2016 to login the linked mailbox, the only way is to use the MA account.
I test login with the PA account in an Original Exchange 2016 CU19 environment.

And I got the same error, I checked the Windows Event Viewer, there are no error logs about it.

I also checked the Exchange 2010, it could use the AD user account which is disabled and has no Exchange attributes as the user account.
For this example, I created the Test User03 as a User mailbox, and then disabled this mailbox, then go ADUC disabled this account.

But in Exchange 2016, you could only choose the Master account and specify the account attributes. Which means Exchange automatically create the disabled account, as the placeholder account for these linked mailboxes.
And as I mentioned above, these users don't use the user logon name to sign in to the linked mailbox. They sign in using their credentials from the account forest.

Regards,
Lou

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