SMTP Connectivity Test
Test SMTP connectivity to a mail server on ports 25, 465 or 587 and see the server banner.
Frequently asked questions
What SMTP ports should be open?
Port 25 (SMTP) is for server-to-server mail. Port 587 (Submission) is the standard for clients sending email. Port 465 (SMTPS) uses implicit TLS. Many ISPs block port 25 to prevent spam.