Mail-Tester
mail-tester.com
Send one email to the address it gives you and get a spam score out of ten
Free tier
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zerobounce.net
Checks a mailing list for dead, catch-all and spam-trap addresses before you send.
Upload a list and it validates each address against the receiving mail server, then classifies them as valid, invalid, catch-all, disposable, role-based or an abuse risk. Running this before a first campaign to an old list is what stops a bounce rate high enough to get your sending domain throttled. It also flags the typo domains — gmial, hotmial — that are otherwise invisible.
AltFTool does this too
If you would rather not leave the site, Email Validator covers the same job here — free, no account, and it runs in your browser.
Open Email ValidatorQuestions
A genuinely usable free tier with paid plans for volume or team features. The free allowance is a small number of monthly credits and needs a verified account; a real list clean is a paid job.
Yes. ZeroBounce sends your input to its own servers to process it. That is fine for public material; for anything containing personal data, use one of the on-device tools instead.
The free allowance is a small number of monthly credits and needs a verified account; a real list clean is a paid job.
Alternatives
Same category or same task, ordered by how closely they overlap.
mail-tester.com
Send one email to the address it gives you and get a spam score out of ten
formspree.io
Gives a static site's contact form somewhere to POST that emails you the answers
mailerlite.com
Sends a newsletter to a small list on a free tier that does not expire
mailinator.com
Any address at mailinator.com already has an inbox you can read without signing up
mailtrap.io
Catches the emails your app sends in a fake inbox so no real person gets them
mxtoolbox.com
Looks up MX, SPF, DKIM and DMARC records and names the one that is wrong