You can reference this question
for background on what I am asking here.
We have an old domain and a new one.
Both domains have Exchange 2010 SP3
Email on the public side goes through owa.domain.com to olddomain.local and then internal relays to any migrated users on the newdomain.local exchange server.
I have all mail flow working fine for everyone EXCEPT this:
Users migrated to the newdomain.local exhange server can't set up their email on smartphones via Microsoft ActiveSync. The AutoDiscover query for autodiscover.domain.com resolves via public DNS/NAT to the olddomain.local exchange server.
Even though the olddomain.local server/domain is going away, we will need simultaneous communication for both servers.
We can't migrate everyone at once due to some other projects so we can only move groups of people at a time.
My thoughts are to direct the IP address of autodiscover.domain.com to the address of newdomain.local's exchange server so the new users can authenticate their phones.
Question: Will doing that cause all existing configurations of smartphones in olddomain.local to stop working or is autodiscover only used for initial setup and once they're set up, the connection will remain?
Am I overthinking this? Is there an easier way to get both domains autodiscovered?