I am setting up a Hybrid configuration between on premise forest A with email @forestA.com and Office 365 forest B with email @forestB.com. What I want to do is assign an email alias to the on premise forest A mailboxes with @forestB.com email. This will allow the on premise mailboxes to start receiving email sent to the O365 domain that they are going to be migrated into. I was hoping to get some tips.
Here is the plan. We are going to add forest B as an accepted domain in the on premise exchange, then add the alias to the users. Then add forest A as a domain in O365 forest B and point the MX record to O365. We have the send and receive connectors in place. Is there anything I am missing? Will mail flow to the on premise mailboxes with the alias added to them? When mail hits O365, will it know the mailbox is on premise even though its an email with a @forestB.com? And will we need to add an additional connector so O365 knows to forward mail to the on premise mailboxes even though the mail is sent to it's own domain? Any help would be greatly appreciated. This is the first big mail project I am doing on my own so I want to get it right.
