Free tool — no signup

SMTP Tester

Connect to any SMTP server with your host, port and credentials, send a test email, and inspect the full SMTP session log — STARTTLS, SSL/TLS or plain. Great for debugging deliverability and auth.

Use these settings in your app, plugin or mail client

Host	mail.maildog.io
Port + encryption	587 + STARTTLS (or 465 + SSL/TLS)
Authentication	Required (normal password / LOGIN / PLAIN)
Username	the full mailbox address, e.g. noreply@yourdomain.com
Password	the mailbox password (Panel → Mailboxes → eye icon)
From address	an address on your verified domain

Common mistakes

Port 587 with "SSL/TLS" fails with wrong version number. 587 needs STARTTLS; only 465 uses SSL/TLS.
Port 465 with STARTTLS hangs until it times out. Choose SSL/TLS for 465.
Encryption set to None: your password is never sent, so the server answers 554 Access denied.
Username without the domain (just "noreply") gives 535 Authentication failed.
No reply at all? Your host may block outgoing SMTP ports. Try 587, then 465.

Connection

Host

Port

Username

Password

TLSRecommended port:

Message

From

Subject

Body

SMTP Session Log

Fill in the connection details and click "Send Test" to begin.

Want unlimited testing, a capture inbox and webhooks? Create a free account