I'm glad the webmail access is working well for you now.
In the port list you provided, I don't see that port 25 is open for traffic. You'd want to make sure that is open as that will allow you to both send and receive messages properly.
If the port is opened on your local firewall, it's possible that your hosting provider is blocking that port on their network, as many providers do. You can test that by running the following command:
That will tell you if you can reach an external mail server. If you can't, port 25 is likely blocked by your provider and you would need to use a third-party email service to send messages properly.
If you get an error that telnet is not installed, you can install it quickly with this command so you can perform the test.