What can be checked, and what cannot
Four things can be checked from here: that the address is written correctly, that its domain exists, that the domain has a mail server, and that it is not a throwaway or a shared role address. What cannot be checked is whether that particular mailbox exists — only the receiving server knows, and modern servers deliberately accept everything to stop exactly this kind of probing.
What each verdict means
- Looks deliverable — valid syntax and the domain has mail servers.
- With a caveat — it will probably work, but it is a role address, a disposable domain, or the domain has no MX and mail would land on the web server.
- Will not work — broken syntax, or a domain with nowhere to deliver.
How to use the verifier
- Paste up to twenty addresses, one per line.
- Press Check them. Each domain's MX records are fetched over DNS-over-HTTPS from your own browser.
- Look at the caveats — the typo suggestions catch the most common sign-up mistakes.
Cleaning a mailing list
- Remove anything marked "will not work" before importing — bad addresses hurt your sending reputation more than a smaller list does.
- Role addresses often go to several people and are more likely to be marked as spam. Keep them separate.
- Disposable addresses were made to receive one message. Blocking them at sign-up is usually worth it.
- For a list you bought, nothing here will save you. Send only to people who asked.
Related checks
To see whether your own domain is set up to send mail properly, use the MX, SPF & DMARC checker. To see whether an IP is on a block list, use the email blacklist checker.
Frequently asked questions
Can you check whether an email address really exists?
Not reliably, and no honest tool can. Most mail servers accept any address at the SMTP stage to prevent harvesting. What can be checked is the syntax, the domain and its mail servers.
What does "no MX record" mean?
The domain has not published a mail server. Mail would be attempted on its web server instead, which usually fails. For a working domain it is a sign the mail setup is missing.
Is my list uploaded anywhere?
No. The checks run in your browser and only DNS queries leave your device — the addresses themselves are never sent to us or anyone else.