Built because guessing was expensive.
MailProof started as a side-panel extension for checking one address at a time. The tool was useful; the problem turned out to be bigger.
The problem with most verifiers
Almost every email verification service sells certainty it cannot deliver. They claim a mailbox exists because a mail server did not immediately refuse it — but Gmail, Outlook and every large provider accept whatever recipient you offer and decide afterwards, out of sight. The confident green tick is, quite often, a coin flip with good branding.
We took the other position. MailProof runs the checks that produce real evidence — syntax, live DNS, MX records, disposable providers, role accounts, typo distance — and tells you what each one found. Where a mailbox genuinely cannot be proven to exist, the result is risky, not valid. It is a less impressive number on a marketing page and a far more useful one in practice.
What it is now
A verification console you can use without an account, a JSON API with no key, and a browser extension for the moments when you just want to check one address without leaving the page you are on. Lists are processed in memory and discarded; there is no database behind this holding your contacts.
Where it is going
Verification is the first honest step in a longer chain. The plan is to grow MailProof into the platform that handles the rest of it — saved lists and segments, scheduled re-verification so a list stays clean between sends, deliverability monitoring, and eventually campaign building and sending itself.
The order matters. Plenty of tools will happily send a campaign to a list nobody checked. Starting from verification means everything built on top of it inherits the same standard: show the evidence, and never claim more than the data supports.
How it is built
Next.js on Vercel, with verification running in serverless functions that resolve DNS over HTTPS. There is no queue, no worker pool, and no persistent store to leak. That keeps it fast, keeps it cheap, and keeps the privacy promise simple enough to actually honour.
Get in touch
Feedback on a result you disagree with is the most useful thing you can send us — it is how the scoring gets better. The contact page reaches a real person.