Should not be public
Port 143 — IMAP
Mail access that leaves messages on the server and syncs across devices.
Port
143
Service
IMAP
Protocol
TCP
Security guidance
Use IMAPS on 993 instead; plain IMAP exposes credentials.
Is port 143 open on your server?
Test it from outside your network — the only view that matters.
Other common ports
20 · FTP data
21 · FTP control
22 · SSH / SFTP
23 · Telnet
25 · SMTP
53 · DNS
80 · HTTP
110 · POP3
123 · NTP
161 · SNMP
389 · LDAP
443 · HTTPS
445 · SMB
465 · SMTPS
587 · SMTP submission
993 · IMAPS
995 · POP3S
1433 · Microsoft SQL Server
1521 · Oracle Database
2082 · cPanel
2083 · cPanel (TLS)
3000 · Node.js / dev server
3306 · MySQL / MariaDB
3389 · RDP
5432 · PostgreSQL
5900 · VNC
6379 · Redis
8080 · HTTP alternate
8443 · HTTPS alternate
9200 · Elasticsearch
27017 · MongoDB