SMTP diagnostics, from your browser

Enter a hostname and port. smtplens opens a real SMTP connection, reads the server banner, and reports what the server supports — no terminal required.

Probe a server See plans

What it does

When email stops working, the useful question is what the mail server says to a client that connects to it. smtplens answers that directly.

→ Opens a raw TCP or TLS connection to the server on standard mail ports (25, 465, 587)
→ Reads the SMTP greeting banner — the raw reply your server sends to every connecting client
→ Sends EHLO smtplens and displays the full capability response — what STARTTLS, AUTH mechanisms, and extensions the server advertises
→ Measures handshake duration so you can spot latency issues

Who this is for

● Small-business owners and junior IT staff diagnosing mail delivery problems
● Developers verifying a mail server they just configured
● Anyone who would check by hand with openssl s_client or telnet, but prefers a browser

How it works

1. Enter the hostname and select a port (25, 465, or 587)
2. smtplens connects directly to the server from its probe endpoint
3. Results are returned, displayed, and immediately forgotten — no data stored

Try it now

No sign-up required. Enter a hostname and see what your mail server has to say.

Open the probe tool