MX Lookup and SMTP Test
Check a domain's mail servers and test SMTP connections, STARTTLS and open relay.
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About this tool
Check a domain's mail servers and test SMTP connections, STARTTLS and open relay.
XGM resolves the MX records, then connects to up to three mail servers on port 25 from its server: it reads the banner, sends EHLO, upgrades with STARTTLS and checks the certificate, and tests relaying with an outside sender and recipient (RFC 2606 example domains). It stops before DATA, so no message is ever sent. On ports 465 (implicit TLS) and 587 (STARTTLS) it reads the banner, the TLS version and certificate, the EHLO extensions and AUTH mechanisms before and after TLS, and never tries to log in. Each step is timed.
How to use it
- Open the MX & SMTP tool.
- Enter the public domain, hostname or IP address you want to check.
- Run the check; XGM queries it from its server and lists the findings.
- Copy the output only after checking it looks correct.
- Use related XGM tools if you need a broader diagnostic view.
FAQ
Is the MX & SMTP free to use?
Yes. The MX lookup is free and works without creating an account.
Does XGM store my input for MX & SMTP?
Browser-side utilities process input locally. Server checks send only the domain, host or IP you enter to the XGM API and do not store it.
Can I use MX & SMTP for production checks?
Yes, use it for quick validation and troubleshooting. For critical changes, confirm the result with your official provider, logs, monitoring or security stack.
What should I do after using the MX lookup?
Compare the result with related signals, save useful evidence and follow the linked XGM guide or related tools if you need a wider check.
Read the full MX Lookup and SMTP Test guide