Source - Exchange 2010 SP3

Target - Exchange 2013 SP1 

We are in the midst of a forklift AD migration. In doing so we are upgrading/migrating our existing Exchange 2010 environment to Exchange 2013. So far so good. I have migrated a few pilot users without issue. Free/busy is good. Mailflow is good. 

My question revolves around shared mailboxes. What is the best method for a user who resides on Exchange 2013 (source) to access a shared mailbox on Exchange 2010 (target).

These users were given full mailbox permission originally before migration. We do have SID history turned on. They would open the mailbox from within outlook using their own profile. I can get them to open the shared mailbox if they close outlook and open a profile with the shared mailbox, but I would rather they continue to work the way they are used to. 

Thoughts?

Hi,

If the Exchange 2013 users want to access the shared mailbox in Exchange 2010 cross forest, the users in Exchange 2013 forest should be resolved in Exchange 2010 forest for shared mailbox to access.

Please do a GALSync from Exchange 2013 forest to Exchange 2010 forest. Then the Exchange 2013 account can be synced to Exchange 2010 forest. Add the full access permission to shared mailbox for this synced account. Then remove and reopen the shared mailbox in Outlook to have a try:

Add-MailboxPermission -Identity SharedMailbox -User DomainB\UserB -AccessRights FullAccess

If the issue persists though the Exchange 2013 account can be resolved in Exchange 2010 forest, please remove the SID history for this mailbox to have a try.

Re

Thanks for the reply. Upon further investigation, I am able access shared mailboxes via owa using my migrated user. Now, can I open that shared mailbox in outlook while logged into my main profile?