How accurate is Valid Email Checker?

Valid Email Checker delivers 99.5% accuracy across the verification engine. That number is measured by running benchmark lists with known good and known bad addresses through the system and comparing our results to ground truth.

The 3% bounce rate guarantee

Here is where we put the math behind the claim. We guarantee that no more than 3% of emails marked as Safe will bounce when you send to them. Not a target. Not an aspiration. A guarantee.

If your bounce rate on Safe-marked emails exceeds 3%, we refund the difference in credits. You verify your list, you send only to Safe results, you track the bounce rate. If it exceeds 3%, you get credited back. Simple.

Why accuracy is hard to pin down with one number

Different verifiers measure accuracy differently, and most do not publish their methodology. A tool that confidently says every address is "valid" is 100% accurate on valid addresses but useless on invalid ones. The honest version of the question is: what percentage of definitive results are correct, and what percentage of results are definitive in the first place?

On the first part, we hit 99.5%. On the second, our engine has two safety nets that most tools do not:

• If our primary verification engine can't deliver a definitive answer, we automatically retry through a second engine before reporting unknown.
• If both come back inconclusive, the credit is automatically returned to your account. You only pay for definitive results.

Where verification gets fuzzy in practice

Two cases give every verifier trouble. The first is catch-all domains, where the mail server accepts every address on the domain whether the mailbox actually exists or not. We flag those as Catch-All so you know to send with caution, rather than guessing. The second is greylisting, where servers deliberately refuse the first connection from any sender and accept the second. We retry on greylisting, so it does not artificially inflate our unknown rate.

The practical implication: if you upload a 10,000-address list and we report 200 as Catch-All, those 200 are not failures of the verifier. They are addresses where the domain itself does not give us a definitive answer. You decide whether to send to them — usually you send with extra caution, monitor reply rates, and remove the non-engagers after one or two sends.