SMTP Server Tester
Interactive SMTP test on port 25, 465 or 587 with TLS, MAIL FROM and RCPT TO checks.
Tests connection, TLS, optional AUTH (PLAIN/LOGIN), and envelope addresses. No message body is sent. Credentials are never cached or logged.
About this tool
The SMTP Tester runs an interactive session against a single mail server port — 587 (STARTTLS submission), 465 (implicit TLS) or 25 (server relay). It reads the banner, negotiates TLS where supported, inspects the certificate, lists AUTH methods and optionally tests MAIL FROM and RCPT TO envelope addresses without sending a message body.
Use it to verify a mail server before going live, debug rejected recipients, confirm TLS is working on submission ports, or score your server's SMTP configuration at a glance.
Frequently asked questions
Does this tool send actual email?
No. The test stops after optional RCPT TO validation. No DATA command is issued and no message content is transmitted.
Why test MAIL FROM and RCPT TO?
These envelope addresses control whether the server accepts a message for delivery. Testing them reveals relay restrictions, invalid sender policies and whether a recipient is recognized — without sending spam.
What is the SMTP test score?
A weighted score from connection, TLS, certificate validity and envelope tests. 80+ means the server passes the checks you ran; lower scores highlight specific failures to fix.