What does SMTP diagnostics test?

SMTP diagnostics connect to a mail server on port 25, perform an EHLO handshake, and measure response times. It helps identify email delivery problems.

Why would SMTP connection fail?

Common causes: the mail server is down, port 25 is blocked by a firewall, the server doesn't accept connections from your IP range, or the mail service uses a different port.

EMAIL Tool

SMTP Diagnostics

Test SMTP server connectivity on port 25, perform EHLO handshake, and measure response times.

About this tool

SMTP diagnostics connect to a mail server on port 25, perform an EHLO handshake, and measure SMTP response times. Essential for troubleshooting email delivery problems. Note: does not test open relay or send actual email messages.

Disclaimer: Results provided by this tool are for informational purposes only and do not replace professional technical analysis. This site is not responsible for decisions made based on this data. See our Terms of Service for more information.