I have a custom receive connector listening on 18.104.22.168 port 25 which allows anonymous for my internal app servers. I'm aware the default connector also listens on 22.214.171.124 port 25. Some application servers are failing to route emails and upon investigation they are hitting the default connector and bouncing with a 5.7.1.
The receive connector is listening on SMTP.domain.local and the apps are configured to send to that but some do and some don't. I'm sure in deployments in the past I have never had to setup the receive connector with a different port 2525 for example or an additional IP
Any ideas why this is happening?