-# The standard port for this purpose is port 587, the "message submission"
-# port. See RFC 4409 for details. Microsoft MUAs cannot be configured to
+# The standard ports for this purpose are:
+# port 587, the "message submission" port - see RFC 4409 for details,
+# and 465 the TLS-encrypted "submission" port, service name is "submissions",
+# see RFC 8314.
+
+# Microsoft MUAs cannot be configured to