Questions
Which port should I use?
Use 587 with STARTTLS to send mail from an app or website; it's what Gmail, Outlook and most providers expect. Port 465 also works and encrypts from the first byte. Port 25 is for servers passing mail to each other and is often blocked for normal senders. 2525 is an unofficial alternative some providers offer when 587 is blocked.
Is it safe to enter my SMTP password?
The password is sent over HTTPS, used once to sign in to the server you named, and then discarded. It is never stored or logged, and the transcript we show has it removed. If you'd rather not use your main password, create an app password with your email provider and delete it after testing.
Why does it say the certificate isn't trusted?
The server's TLS certificate is expired, self-signed, or issued for a different name than the one you typed. Email clients will show the same warning. Tick "Allow an untrusted certificate" to finish the test anyway, then fix the certificate on the server.
The connection times out. What does that mean?
Usually a firewall or the hosting provider blocks that port. Try 587 or 465, or run the SMTP port check to see which ports answer.
More email tools
- Check which SMTP ports are openTest all four mail ports of a server at once and see which answer, which are blocked, and what the server says when it picks up.
- MX lookupSee which mail servers receive email for a domain, in priority order, with their IP addresses and a quick health check.
- SPF and DMARC checkerCheck whether your domain's SPF and DMARC records are set up correctly, in plain language, so your email reaches the inbox and nobody can pretend to be you.
- DKIM checkerFind a domain's DKIM public key under the selectors common providers use, or the one you enter, and check its type, length and settings.
- Email blacklist checkCheck an IP address, or a domain with its mail servers and website, against Spamhaus, SpamCop, Barracuda and 13 other spam blocklists at once.
- Email warmup plannerPlan how fast to raise your sending volume on a new domain or mailbox, day by day, so Gmail and Outlook learn to trust you instead of sending you to spam.