So we have 3 ad forests that are trusted. In forest A we have the majority of users and computers and the exchange server. In forest B we have users and computers and the users have linked mailboxes on the exchange server in forest A. In forest C we have users and computers and the users have seperate users with "normal" mailboxes on the exchange server in forest A. They just use the separate login information to connect to the mailbox in outlook and then save credentials.
We now want to move all mailboxes to O365 via Exchange Hybrid and we already installed AADConnect in forest A. The question is on how to do the user matching in this szenario because it is not a classic exchange resource forest scenario.
The end goal is to merge the forests in to one but we are far away from this.
Whats the best way to do the user matching here?
One other idea was to migrate the mailboxes (about 200) from forest B and C with a 3rd party tool to O365 first and convert their mailboxes in forest A to mail users with a target address that will not be synced to O365.