I’ve had this issue for years now and I thought I would give it another go, but low an behold your still broken. What is the problem? My firewall is open to your program and nothing else is blocking it. I am on a fresh build so it should work, but it doesn’t. I have to use Spark and that works, so why cant EM client?
I am using eM client with Virgin Media in the UK with no issues at all (for years). I suspect that you need to check / change the ports that you use to connect to your mail server. Are you using a commercial email server (eg Yahoo, Gmail etc) and is the issues with sending / receiving or both?