Hello,
So im moving some users to office 365 from SBS2011. After moving a single user and making the connections between office365 and Exchange all mailflow is working but I get an NDR with IMCEAEX- when replying internally (another user within Exchange) to an old email from the user or selecting the user from the Outlook address cache. I cant have all the users delete ithe cache or have them change the address when replying to old messages, so I need a way to route those messages to the external contact Ive created or to the new server.
I keep reading that you have to assign an X500 address to the old user, and the value of legacyexchangedn but dont know exactly where Im supposed to assign it, the mailbox doesnt exist anymore on Exchange (the user account does). Do I assign it to the external contact Ive created within the Exchange org? Please help.