Port 465: SMTPS
TCP 465 is the port for SMTP submission over implicit TLS. Fine on mail submission servers; requires authentication.
| Service | SMTP submission over implicit TLS |
|---|---|
| Protocol | TCP |
| Exposure risk | Low: normally safe to expose |
| Range | Well-known (0–1023): binding needs root/admin on Unix |
What port 465 does
Mail clients submit outgoing mail with TLS from the first byte. RFC 8314 (2018) re-registered 465 for this and recommends it over STARTTLS on 587.
Should port 465 be open?
Fine on mail submission servers; requires authentication.
Find what's listening on port 465
- Linux:
sudo ss -tulpn | grep :465 - macOS:
sudo lsof -nP -i :465 - Windows:
netstat -ano | findstr :465, then look up the PID in Task Manager.
Open or block it in a firewall
- ufw:
sudo ufw allow 465/tcp(ordeny) - firewalld:
sudo firewall-cmd --add-port=465/tcp --permanent && sudo firewall-cmd --reload - Windows:
New-NetFirewallRule -DisplayName "Port 465" -Direction Inbound -Protocol TCP -LocalPort 465 -Action Allow
Port assignment per the IANA Service Name and Transport Protocol Port Number Registry. Test several ports at once with the port scanner, or any port with the open port checker.
Questions about port 465
What is port 465 used for?
SMTP submission over implicit TLS. Mail clients submit outgoing mail with TLS from the first byte. RFC 8314 (2018) re-registered 465 for this and recommends it over STARTTLS on 587.
Is port 465 TCP or UDP?
TCP. SMTPS uses TCP port 465.
Is it safe to open port 465?
Low: normally safe to expose. Fine on mail submission servers; requires authentication.
How do I check if port 465 is open?
Use the checker on this page: it connects to your host on TCP 465 from the internet. Locally, run
nc -vz host 465 (macOS/Linux) or Test-NetConnection host -Port 465 (PowerShell). To see what is listening on your own machine, run ss -tulpn | grep :465 (Linux) or netstat -ano | findstr :465 (Windows).