Current setup -
Domain abc.com ~150 users - Exchange 2013 - Domain/Forest functional level: Server 2008 R2
Acquired xyz.com ~150 users - Exchange 2010 - Domain/Forest functional level: Server 2008 R2
Offices/locations are going to remain separate for now. To the outside world abc.com and xyz.com will still be operating as two distinct companies.
The requirements -
Keep existing domains, abc users should use their @abc credentials, while xyz users retain @xyz credentials
Share Free/busy between domains
Access to schedule the same resources - (xyz user will be in the office of abc and needs to schedule a room)
One mailbox/instance to manage(The boss wants to be able to send/receive abc/xyz without changing profiles)
Solution?
This is what has been asked by the leadership team in the next 30 days(the sooner the better).We will eventually combine/condense the forests but that is not an option at this time. I know each one of these items can be solved with existing tools(forest trusts, free/busy federation etc).
My initial thought given the timeline, is to create a PtP VPN between sites, and create Forest trusts. Create a new mailstore/database on the abc.com exchange server and migrate xyz mailboxes to the 2013 instance. Upgrade the 2010 instance to 2013 and addit to the existing 2013 setup.
My question is how can I setup the migrated mailboxes to point to the xyz.com AD account for auth? Since these are existing user mailboxes I do not think they can be turned into linked mailboxes for exchange federation. But if they could, would that solve the requirements above?
Understanding this is not the ideal way to do this, on this timeline, what would you do? Are my thoughts inline with what can be done?