If a cPanel account has Remote Mail Exchanger selected, Does this mean email will send out the local server to the remote server (as I understand this to be)
If a cPanel account/domain is using a remote mail exchanger this means that the MX records for that domain are pointed to a remote location. This means that mail sent to the domain will arrive at the remote destination but mail sent from the server will still be sent from the server it will not be sent from a remote location unless the user is accessing that location and this can cause issues with mail if users send locally instead of where mail is hosted.