Port 465 is Normally the Implicit SSL SMTP Port, but not always…

If you open a DOS prompt and telnet to an SMTP server (typically port 25 for non-SSL, port 465 for SSL), you should get a human-readable printable-text “HELLO” message from the non-SSL port, but binary SSL-handshake protocol gobbly-gook from an implicit SSL port. For example: > telnet mail.chilkatsoft.com 25 220 …