A list of email-server relevant ports#

For future reference ;)

SMTP#

PortDescription
25SMTP relay; usually plain text, can be TLS enc.
2525Alternative to 25 with possible TLS enc.
465Implicit SSL, no longer accepted standard
587IANA reg. as secure SMTP, req. TLS conn.

POP3#

PortDescription
110Default, no enc.
995Secure POP3 with TLS or SSL

IMAP#

PortDescription
143Default, no enc.
993Secure IMAP with TLS or SSL