Email address checker
Check one email address before you send to it or store it: syntax, typos, whether its domain takes mail, disposable services, role addresses and Gmail’s own rules. It runs in your browser.
Questions
What does the checker test?
Syntax against the email standards (RFC 5321 and 5322, including the 64-character limit before the @ and 254 overall); whether the domain exists and has mail servers, including null MX (RFC 7505) and domains with no MX record; typos in popular providers (gmial.com) and in endings that don’t exist (.con); the open-source lists of more than 100,000 disposable email domains; role addresses such as info@ and noreply@; Gmail’s username rules; and which provider runs the mailbox.
Can it tell whether the mailbox exists?
No. Only the receiving mail server knows, and a browser can’t talk to mail servers. Even asking the server directly is unreliable on its own: catch-all domains accept every address, and many servers slow down or block unknown senders who ask. A mailbox validation service such as ZeroBounce does that work, plus spam trap and abuse detection.
Where does the address go?
The checks run on this page. DNS questions about the domain go from your browser to Cloudflare’s public resolver, or Google’s as a fallback. For the disposable lists, only the first two characters of a hash of the domain reach tanase.ai. The address is put in the page link so you can share the result; opening such a link sends it to tanase.ai like any web address, as the privacy page explains.
Why is a role address flagged?
Addresses such as info@, sales@ or noreply@ reach a team, a system or nobody, not one person. They are fine for business contact. Many senders keep them off marketing lists, because nobody in particular signed up and more than one person reads them.
Do dots and plus signs matter in Gmail addresses?
Not for gmail.com. Google ignores dots in Gmail usernames and delivers jane+news@gmail.com to jane@gmail.com, so the checker shows the mailbox an address really reaches, which helps spot duplicate sign-ups. Work and school accounts on their own domains keep their dots. Most large providers, including Microsoft 365, also accept +tags.
Why warn about a typo when the domain exists?
Domains one keystroke away from big providers, such as gmial.com or hotmial.com, are often registered to collect mail meant for someone else. An address there is far more likely a slip than a real mailbox, so the checker suggests the likely fix.
Why does it link to ZeroBounce?
tanase.ai is built by Liviu Tanase, founder and CEO of ZeroBounce, an email validation company. The checks here are free and stop where a browser has to stop; ZeroBounce validates the mailbox itself. The link carries his referral code.