Network Tools

Email diagnostics

SMTP Test Tool

Inspect a mail server's live greeting, EHLO capabilities, STARTTLS upgrade, certificate, timing, and clean shutdown.

Read-only protocol check. Octetify sends only EHLO, STARTTLS, and QUIT. It never authenticates, tests a mailbox or relay, creates a mail transaction, or sends email. The destination sees Octetify's connection IP and fixed EHLO name.

Choose a destination

Test a domain's ordered MX hosts on port 25, or connect directly to a public SMTP host.

Test mode
?

Enter a domain name without a URL, path, username, or password.

Connection plan
STARTTLS on port 25
Examples:

Public destinations only · 40-second diagnostic limit

What this proves: the selected public server accepted a TCP connection and returned the protocol evidence shown below at the time of the test.

What it cannot prove: message deliverability, authentication, relay policy, recipient existence, spam placement, or future availability. Port 25 TLS is commonly opportunistic; submission ports are assessed more strictly.