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How to ensure that mailboxes have the correct OAB in place (migrating from Exchange 2010 to Exchange 2016).


I am in my last phase of migrating from Exchange 2010 to Exchange 2016.  All mailboxes have been moved to 2016.  I am using the following document to perform the migration.  


My next step requires for me to Remove unused Offline Address Book (In Part 6).  

I do not see a step that defines mailboxes to use the Exchange 2016 OAB.  Is there such a step involved?  I want to make sure I don't miss anything before I can safely select and removing the 2010 OAB.

Thanks in advance.

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3 Solutions
You can check the oab details at database level.

Exchange UserSystems AdministratorCommented:
When you create a new OAB for 2016. You can go into the database properties and point the database to the new OAB manually.
realtimerAuthor Commented:
Thank you everyone.  Just to confirm, here are the results of the commands.  Seems like I need to manually add it.
1. Can you verify?
2. How can I check at the mailbox level to ensure that each mailbox has the correct OAB?

Default Offline Address List            {Version2, Version3, Version4}          {\Default Global Address List}
Default Offline Address List (Ex2013)   {Version4}                              {\Default Global Address List}

Run the following command to view all the mailbox databases in your organization and the OABs assigned to them.
Get-MailboxDatabase | Format-Table Name, Server, OfflineAddressBook -Auto:
Name     Server     OfflineAddressBook
Staff1     FOEX03   -blank-  (nothing listed)

For every mailbox database that doesn't have an OAB assigned, assign an OAB from the list you retrieved earlier. You can either individually set the OAB on each mailbox database or simultaneously set the OAB on all mailbox databases. Use the command below that best suits your requirements.

In EAC, Servers | Databases | Staff1 (Exchange 2016 database) | Edit | Client Settings:
Offline Address Book is -blank-
When I click Browse... I see options:
Default Offline Address List (I presume this is the 2010 OAB)
Default Offline Address List (Ex2013) (I presume this is the 2016 OAB).

Should I manually select "Default Offline Address List (Ex2013)?  
...and how do I check the mailboxes to ensure they are using the 2016 OAB?

Thanks again.
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Exchange UserSystems AdministratorCommented:
Yes you will have to manually select the correct OAB (as long as you have made that OAB default)

The best way to verify is when you make changes to the GAL, check the changes on the Outlook's address book after 24 to 48 hours to see if it picked up the change.

And when Outlooks are pointed to the wrong OAB or no OAB, they give an error when you try to manually update OAB on the Outlook level (I'm not 100% about that but I did come across this issue once at work, after investigation, i figured out that the default OAB got corrupted and I had to create a new one).
realtimerAuthor Commented:
Thank you -

Sorry about possibly dumb question, but I'm being very cautious due to very sensitive customer.  What do you mean "as long as you have made that OAB default".  No OAB specific changes have been made beyond OAB being created during the 2016 install.
Exchange UserSystems AdministratorCommented:
Set-OfflineAddressBook -Identity "My OAB" -IsDefault $true

Check this link out:

realtimerAuthor Commented:
Thank you very much everyone.
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