After migrating all our users from the old server to the new one, email does not seem to flow internally. users are able to send and receive external emails though.
The new server is setup with Mailbox and Client Access roles. And has the following receive connectors:
Client Frontend "servername"
Client Proxy "servername"
Default SMTP Internal Relay
Outbound Proxy Frontend "servername"
Where should are start looking to solve this issue?