active directory – Exchange Migration without outlook configuration

I am working on migrating some users from Exchange1 and Domain1 users to Exchange2 and Domain2.

I am able to migrate their accounts from Domain1 to Domain2 with their current password. No issues.

I am able to migrate their mailbox from Exchange1 to Exchange2 while linking to their new Exchange2 mailbox.

I can now login to the new Exchange2 mailbox by OWA using Domain2user and their existing password everything is there no problem.

I then update the autodiscover in my dns to point to Exchange2.

My problem is none of the Outlook clients connect at this point. When opening Outlook all I get is “Disconnected” at the lower right, no prompt to enter a password, nothing. If I remove the account from Outlook and configure it again it works properly.

Is there something I can do to save our team of reconfiguring 300 plus Outlook clients?