What is port 465 used for?
Email submission with implicit TLS: the connection is encrypted from the first byte.
Should port 465 be open?
Usually open to the internet. This port is meant to be reachable publicly on servers that offer the service. RFC 8314 recommends implicit TLS for mail clients; 587 with STARTTLS is equally common. Both need authentication.
See what is listening on port 465
# Linux
sudo ss -tlnp | grep ':465 '
# macOS
sudo lsof -nP -i TCP:465 -sTCP:LISTEN
# Windows (PowerShell)
Get-NetTCPConnection -LocalPort 465 -State ListenOpen or block port 465 in a firewall
# Ubuntu / Debian (ufw)
sudo ufw allow 465/tcp
sudo ufw deny 465/tcp
# Windows (PowerShell, as administrator)
New-NetFirewallRule -DisplayName "Port 465" -Direction Inbound -Protocol TCP -LocalPort 465 -Action AllowOn cloud servers, also open the port in the provider’s security group or network firewall. At home, a service behind a router needs a port-forwarding rule to the device’s local IP.
Test it from outside
A port can be open on the server but blocked upstream. The Port Checker connects from the internet, so it shows what the world sees. From your own machine, use nc -vz example.com 465 (macOS/Linux) or Test-NetConnection example.com -Port 465 (Windows).
Port CheckerTest whether a server accepts connections on specific ports — web (80/443), mail (25/587/993), SSH, databases or remote desktop — and see which are open, closed or filtered by a firewall.
Open the tool Frequently asked questions
What is port 465?
Email submission with implicit TLS: the connection is encrypted from the first byte.
Is it safe to open port 465?
Usually open to the internet. This port is meant to be reachable publicly on servers that offer the service.
How do I check if port 465 is open?
Enter your domain or public IP in the Port Checker with port 465. It tries a TCP connection from the internet and reports open, closed or filtered.