Port & Mail Server Connectivity Tester

Opens a direct TCP connection to the common mail, web and sysadmin ports on a host, grabs whatever banner the service volunteers, and checks whether the plaintext mail ports advertise STARTTLS. Note: many hosts (including most shared/cloud hosting) block outbound port 25 entirely, so a closed 25 here can reflect this checker's own network rather than the target server.

📖 Guide: Mail & web ports explained

Last updated: August 29, 2026