I turned the "SSL" boxes off on both the SMTP and POP servers and got mail right away. It appears to be working as it should now. I am going to go check what "SSL" is.
SSL is an encrytion layer that depending upon how it's implemented may not be totally compatible with the way things are set up. Making matters worse, it's evolved over the past couple of years and there are several versions. It's basically hit or miss if you're using TLS1.0 or TLS1.1 for SSL at the moment, as most systems have moved to 1.2 (or even 1.3).
But regardless, glad everything is working now.