IANA has already assigned TCP port 465 for "submissions" as described by RFC8314. See https://www.iana.org/assignments/service-names-port-numbers/service-names-

IANA has already assigned TCP port 465 for "submissions" as described by RFC8314. See https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?&page=9 https://www.iana.org/assignments/service-names-port-numbers/... The other service already assigned TCP port 465 was URL Rendezvous Directory for SSM (URD).