Port 465 should no longer be used at all

Port 465

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 an SMTP port by the Internet Assigned Numbers Authority (IANA).

This port was initially used for the SMTPS encryption and authentication “wrapper” over SMTP. It was introduced to securely send emails using Secure Sockets Layer (SSL). SSL was commonly used for encrypting communications over the internet. By the end of 1998, IANA has reassigned this port number for a new service. But, still many services continue to offer the deprecated SMTPS interface on port 465. Service providers that maintain port 465 do so because older Microsoft applications do not support STARTTLS.

Don’t use port 465, because this port is no longer an accepted standard for SMTP.

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