pfSense

In Firewall > Rules, the table displayed has a column named "port" which helpfully shows not just the port number, but a name too, like http, https, smtp, etc.

For port 465, the name "smtp/s" is used. As you may know, port 465 has a messy history; the footnote on wikipedia summarizes it nicely:

"TCP port 465 was originally assigned to allow the use of SMTP over SSL (SMTPS), but practical concerns meant that it was left unused and according to the registration rules at that time was subsequently revoked and eventually re-assigned for use by Cisco's URD protocol. Subsequently, port 587 was assigned as the SMTP submission port, but was initially in plaintext, with encryption eventually provided years later by the STARTTLS extension. At the same time, the subsequent adoption of the usage of 465 as an SSL-enabled SMTP submission port, even though the original registration did not envision that usage and despite the fact that it was registered to another service has endured. Subsequently, RFC 8314, in a special exemption to the normal assignment process as defined by RFC 6335, acknowledges the de-facto situation and not only designates message submission over implicit TLS as an 'alternate usage assignment' but establishes this as the preferred method and calls for transition away from port 587 and STARTTLS."

By far now, the main use of TCP 465 is for 'submissions' (not plural, but 's' for SSL, like http vs https).

It would be nice for pfsense to switch from showing 'smtp/s' to 'submissions'.