Port / TCP
995POP3S
POP3 inside TLS from connect time, for clients that download and store mail locally.
If it is internet-facing: Port 995 is routine where it is expected. Its risk lives in the service configuration behind it, not the port itself.
Exposure
Internet-facing
Transport
Encrypted by default
Risk if public
Low
Exposure verdict
Port 995 is meant to answer from the internet, and it protects the session itself. What remains is authentication strength, patch level, and rate limiting.
The session is protected from the first byte, so there is no plaintext phase for an on-path attacker to strip or read.
Assigned by IANA through a review process. On Unix systems a process needs root or the CAP_NET_BIND_SERVICE capability to bind here, which is why containers so often remap these to a higher port.
Grouped with the other mail ports so a rule written for one can be checked against its neighbours.
What actually goes wrong
1 note- Preferred over STARTTLS on 110 because there is no plaintext phase to strip.
Recommended firewall rule
Allow it, and harden the service
This port is expected to answer from anywhere, so the firewall is not where its security comes from.
ufw
sudo ufw allow 995/tcpiptables
sudo iptables -A INPUT -p tcp --dport 995 -j ACCEPTCheck what is really there
Listening locally
sudo ss -tlpn 'sport = :995'The bind address is the answer that matters: 127.0.0.1 is local-only, 0.0.0.0 and :: mean every interface.
Listening (macOS)
sudo lsof -nP -iTCP:995 -sTCP:LISTENmacOS ships lsof rather than ss; this names the owning process and user.
From outside
nmap -sV -Pn -p 995 <host>A version probe confirms whether POP3S is actually what answers, rather than trusting the number. Only scan hosts you are authorised to test.
Reachability
nc -vz <host> 995The quick yes/no when you only need to know whether a path exists through the firewall.