DNS & Email Tools
SMTP Diagnostics
Open-port SMTP handshake test with banner and TLS validation.
Updated 2025-12-01
SMTP Diagnostics
Test mail server connectivity, TLS, and configuration
SMTP Ports
About SMTP Diagnostics
- • Port 25: Standard SMTP - often blocked by ISPs
- • Port 465: SMTPS - SMTP over implicit TLS (deprecated but widely used)
- • Port 587: Submission - Recommended for email clients with STARTTLS
- • Port 2525: Alternate - Used when port 25 is blocked
- • Tests TCP connectivity, TLS/SSL certificates, and fetches MX records