SMTP Connectivity Test
Test SMTP connectivity, TLS and authentication to any mail server. Optionally send a test email after a successful connection.
Frequently asked questions
What SMTP ports should I use?
Port 587 (Submission + STARTTLS) is the standard for client sending. Port 465 uses implicit TLS (SMTPS). Port 25 is server-to-server and is often blocked by ISPs. Port 2525 is an alternate submission port some providers use.
Is my password sent securely?
Your credentials are used only to perform the AUTH test against the server you specify. They are not stored, logged, or transmitted anywhere else. On TLS-capable ports the connection is encrypted before authentication is attempted.
What does the Security setting do?
Auto detects the right mode based on port (465 = implicit SSL, 587/2525 = STARTTLS, 25 = plain). SSL forces implicit TLS from the start. TLS forces STARTTLS and fails if unavailable. "TLS when available" tries STARTTLS but continues if the server does not advertise it. None skips TLS entirely.
What does AUTH LOGIN vs AUTH PLAIN mean?
Both are standard SMTP authentication mechanisms. AUTH PLAIN sends credentials in one Base64-encoded step. AUTH LOGIN sends them in two separate exchanges. Most mail servers support both; PLAIN is preferred where available.