Port 993: IMAPS
IMAP over TLS.
- Port
- 993
- Protocol
- TCP
- Service
- IMAPS
- Exposure
- Expose only with access controls
What is port 993 used for?
Encrypted mailbox access.
Is it safe to expose port 993 to the internet?
Fine on a mail server; use strong passwords or app passwords.
If port 993 seems closed or unreachable
- Check that the IMAPS service is running and listening on port 993, not only on 127.0.0.1.
- Check the firewall on the host itself (Windows Defender Firewall, iptables, nftables, ufw) for a rule that allows TCP 993.
- If the host is behind a router, confirm the forwarding rule points to the correct internal address and that your internet provider does not use carrier-grade NAT.
- Test from outside your own network. A port can be open locally and blocked at the edge, or the other way round.
Using port 993 safely
Port 993 can be exposed when the host exists to provide this service, but add controls: restrict source addresses where you can, require strong authentication and encryption, and monitor the logs for repeated failures.
Check whether port 993 is open on your host
The check connects from our server, so it shows what the internet can reach.
Open the port checker