MailProbe opens a real SMTP connection to any mail server, reads the greeting banner, asks what it supports, and reports what it found — the check an admin would do by hand with a terminal, without needing a terminal.
Every probe returns exactly what a mail server advertises to an incoming client — nothing more, nothing less.
The full SMTP greeting line the server sends when a client connects — typically the software name and version the server runs.
Whether the server offers TLS upgrade on plain-text connections. A missing STARTTLS advertisement means unencrypted email transit.
Which authentication methods the server accepts (PLAIN, LOGIN, CRAM-MD5, etc.) — useful for diagnosing client authentication failures.
All EHLO keywords the server advertises: PIPELINING, 8BITMIME, SMTPUTF8, CHUNKING, DSN, ENHANCEDSTATUSCODES, BINARYMIME, and maximum message size.
The elapsed time from TCP connect to EHLO response completion, measured in milliseconds. Helps distinguish slow servers from unreachable ones.
The full bidirectional SMTP conversation, line by line with direction arrows and timestamps — every byte the server sent and every command MailProbe issued.
A real TCP connection, a real protocol exchange, a real answer.
Type the mail server hostname (e.g. mx.example.com) and select a port — 25 (SMTP), 465 (SMTPS), or 587 (Submission).
Our backend opens a raw TCP socket (TLS for port 465) to the server you specified, reads the 220 greeting, and sends EHLO mailprobe.
MailProbe collects the server's multi-line EHLO response, parses every advertised capability, and displays them alongside timing and raw exchange data.
No signup, no credentials, no stored data. Just a real SMTP probe against the server you specify.
Open MailProbe