I’ve just migrated an Exchange 2010
installation to Office 365 using the “cut over” migration method. As it was a
small deployment I did not go through the exact process documented by
Microsoft, instead I did a PST export/import migration. For this, it created an
interesting problem in regards to name resolution for clients in the domain.
Clients would successfully do an Autodiscover, but the internal DNS would
continue to point users to the old Autodiscover service on the Exchange Server.
The following changes were made to prevent
Active Directory resolving the old Autodiscover service;
· Edited the “HomeMDB” attribute from
ADSI Edit (Configuration)
· Disabled (deleted) the Mailbox from
Exchange
· Recreate the Outlook profiles for
each user
Remove the HomeMDB
Attribute using ADSI Edit
Connect to
ADSI Edit, and connect to the Configuration container and find the Microsoft
System Attendant at the following path.
N=Configuration,CN=Services,CN=Microsoft
Exchange, CN= "OU", CN=Administrative Groups,CN= Exchange
Administrative Group, CN=Servers, CN=EXCH", CN=Microsoft System Attendant
Simply
clear out the value in this attribute until it looks like this.
Disable the Exchange
Mailbox (Delete the mailbox without deleting the user)
From the Exchange
Management Console, browse to Recipient
Configuration/Users, select the User and then choose the Disable option.
If you select the Disable option, the Active Directory user object will remain. The
Exchange Mailbox is not actually deleted from the Mailbox Database until the
next purge is carried out, which is determined by your Retention Policy.
Although this work around works fine in a small
environment, it may not be so straight forward in a more complex deployment. It
is possible to configure Autodiscover redirection if required.