Almost every ESP does not accept connections on port 465. Port 465 was never published by the Internet Engineering Task Force (IETF) as an official SMTP transmission channel but was registered as [...]

What is Port 2525?

Port 2525 is used for secure submission of emails for delivery by modern ESPs. Unlike other SMTP ports, you will not find the port block issue with port 2525. As this is a non-standard port for [...]