Expose with care
Port 465 — SMTPS
Email submission over implicit TLS — the client connects and the whole session is encrypted from the start.
Port
465
Service
SMTPS
Protocol
TCP
Security guidance
Fine for mail clients. Modern practice favours 587 with STARTTLS, but 465 is well supported again.
Test port 465 yourself
From your own machine, against any host (swap in your domain):
macOS / Linux — netcat
nc -vz example.com 465
Any OS — nmap
nmap -p 465 example.com
Windows — PowerShell
Test-NetConnection example.com -Port 465
open = a service answered on port 465; closed = the host replied but nothing is listening; filtered = a firewall silently dropped the probe. These test from your network — our port checker tests from the outside, the view that matters for security.
Is port 465 open on your server?
Test it from outside your network — the only view that matters.
Other common ports
20 · FTP data
21 · FTP control
22 · SSH / SFTP
23 · Telnet
25 · SMTP
53 · DNS
80 · HTTP
110 · POP3
123 · NTP
143 · IMAP
161 · SNMP
389 · LDAP
443 · HTTPS
445 · SMB
587 · SMTP submission
993 · IMAPS
995 · POP3S
1433 · Microsoft SQL Server
1521 · Oracle Database
2082 · cPanel
2083 · cPanel (TLS)
3000 · Node.js / dev server
3306 · MySQL / MariaDB
3389 · RDP
5432 · PostgreSQL
5900 · VNC
6379 · Redis
8080 · HTTP alternate
8443 · HTTPS alternate
9200 · Elasticsearch
27017 · MongoDB