Free email address validator
Paste an address and see what is actually knowable about it: whether it parses, whether the domain exists, whether it can receive mail at all, and whether anything about it should worry you.
Free, no signup, no daily limit. We do not store what you check here.
The four questions, in order
Does it parse as a mailbox? Does the domain resolve in DNS? Does the domain publish a route for mail? And does that specific mailbox exist? The first three are answered here, offline and free. The fourth needs a live conversation with the receiving server, and it is the one where most validators quietly guess.
Where other validators produce false positives
Two cases dominate. Consecutive dots in the local part are illegal unquoted, yet plenty of regex-based validators accept a..b@example.com. And RFC 7505 lets a domain publish a null MX record - a single dot - to declare that it accepts no mail whatsoever; a validator that merely counts MX records reads that as a valid mail route. example.com, the address every test suite reaches for, publishes exactly that.
Questions
Can you tell me if the mailbox really exists?
Not from this free tool. That requires an SMTP conversation with the receiving server. The paid API does it, with a control probe so a catch-all server cannot fool it.
What does "inconclusive" mean?
That the evidence genuinely does not settle the question - most often because the domain accepts mail for every address. It is an honest answer, and on the API it is never billed.
Do you store the addresses I check?
No. Free tool checks are answered in memory and not written to a database.
Related tools
Disposable email address checker
Check whether an email address uses a throwaway or temporary inbox provider. Free, no signup.
Catch-all domain checker
Find out whether a domain accepts mail for every address - the reason email validators report false positives. Free.
MX record lookup
Look up the MX records for any domain and see who handles its mail. Free, live DNS query, no signup.
When you need more than a free tool
This page answers what can be determined offline and from public DNS. The API adds live carrier and mailbox verification, a calibrated confidence score, and the full evidence trail behind every verdict.
Credits never expire. Inconclusive verdicts are never billed. Cancel in one call. See pricing or read the docs.