I have a client with Exchange 2016. They have an old phone system and voicemail system that transcribes voicemail to email and sends to the Exchange server for distribution to user mailboxes. The Exchange server stopped receiving email from the voicemail server recently. My suspicion is TLS. The voicemail system does not have any kind of authentication, so obviously no TLS. My question is, would there be a downside to modifying the Default Frontend receive connector scoping to "skip" the IP address of the voicemail server, then create a separate receive connector with scoping for only the voicemail server?
I would create a connector specifically for the scope of that phone system.