Free tool
Email verifier
Paste any business email address. We check the format and ask DNS whether the domain runs a real mail server, the two things that catch most dead addresses before you waste a send.
Honest limits: only the receiving server can prove a specific mailbox exists. Leadistry leads go further, every delivered email is verified against the company's own website and Companies House records. Try 10 free leads, no card needed.
What this check actually does
Every verifiable email address has two public facts attached to it: whether it is syntactically valid, and whether the part after the @ can receive mail at all. The first is a format check against the rules every mailbox provider enforces (one @, a real domain shape, no illegal characters). The second is a DNS lookup for MX records: the published list of servers that accept mail for that domain. A domain with no MX records cannot receive email, so any address on it is dead on arrival, no matter how plausible it looks.
Those two checks catch the majority of bad addresses on a typical prospect list: typos, defunct domains, companies that moved to a new name, and made-up addresses guessed from a name pattern. What they cannot do is prove a specific mailbox exists on a working domain. That final step needs an SMTP conversation with the receiving server, and even then roughly a third of business domains are catch-all, which means they accept every address and reveal nothing.
Why bounce rate matters more than list size
Mailbox providers score senders. When your emails bounce, especially hard bounces to addresses that never existed, your domain's reputation drops, and the mail you send to real people starts landing in spam. Keeping bounces under 2 to 3 percent is worth more than any subject-line trick, which is why verifying a list before sending is the single highest-leverage deliverability habit. If you are sending cold email, pair this with the sending-domain checker so your own SPF, DKIM and DMARC records are in order too.
Frequently asked questions
How does an email verifier work?
In three layers. First, syntax: is the address even shaped like an email? Second, DNS: does the domain publish MX records, meaning it runs a real mail server? Third, SMTP: connect to that server and ask whether the specific mailbox exists. This free tool runs the first two layers, which catch most dead addresses. Only the receiving server itself can confirm the third with certainty.
What is a catch-all domain?
A domain configured to accept mail for any address, even ones that do not exist. Catch-all domains answer yes to every SMTP mailbox check, so no verifier can prove a specific mailbox is real on them. Roughly a third of business domains are catch-all. The honest answer for those is 'risky', not 'valid'.
Why do verified emails still bounce sometimes?
Mailboxes get deleted between the check and the send, servers greylist unknown senders, and catch-all domains accept everything then bounce later. Verification reduces bounces dramatically but no tool can make them zero. Keeping your bounce rate under 2 to 3 percent is what protects your sender reputation.
Is it safe to check an email address here?
Yes. The check reads public DNS records for the domain. We do not send anything to the address, we do not store the addresses you check, and no signup is needed.
How is a Leadistry lead's email different?
Leadistry does not guess first.last@domain patterns. Every delivered email was published by the company itself, usually on its own website, then cross-checked against Companies House records and the domain's mail setup. If we cannot verify an email we deliver the lead without one rather than sell you a guess.
Also free: the sending-domain checker (SPF, DKIM, DMARC). Or skip list-cleaning entirely: Leadistry delivers UK leads with pre-verified emails from Companies House data.