Port 143 is used by Internet Message Access Protocol (IMAP). Email access protocol. Unlike POP3, IMAP keeps email on the server and syncs across devices. Port 143 is the unencrypted version.
What Does an Open Port 143 Mean?
An email server is accepting unencrypted IMAP connections. Credentials and email content travel in plain text. Use IMAPS on port 993 instead.
This port should NOT be open to the public internet on typical systems. If you see it open, investigate immediately.
Security Risk Level
High Risk
How to Check if Port 143 Is Open
Use the ExamineIP Port Scanner to check if port 143 is open on any IP address from the public internet. Enter the target IP and select the relevant port preset.
How to Close Port 143
- Stop the service using port 143 if you no longer need it
- Add a firewall rule blocking inbound connections on port 143
- Check your router for port forwarding rules that expose this port
- Run
netstat -ano | findstr :143(Windows) to see which process is using it
Related Ports
IMAP is related to: {implode(‘, ‘, Array)}
Protect Your Open Ports
If you need services like remote access, use a VPN to create a private encrypted tunnel instead of exposing ports directly to the internet. A VPN also hides your real IP address so port scanners cannot identify your device. Try PureVPN or IPVanish.