About ZapBounce
ZapBounce verifies your list with its own SMTP check and reports two numbers, not one: how much of the list reached a verdict, and how accurate those verdicts are. Unknown results are never billed.
The short version
- Vendors advertise accuracy above 99%. Hunter's field test of 15 verifiers, published 3 November 2025, measured 31.2% to 70.0%.
- Both sets of figures are arithmetically true. They count different denominators, and only one of them reaches the pricing page.
- We report coverage next to accuracy, because either number alone can be improved by making the product worse.
- Unknown is a verdict here, it is never billed, and credits never expire.
The number that started it
Hunter tested 3,000 real business addresses across 15 verifiers and published the results on 3 November 2025. Overall accuracy ran from 31.2% to 70.0%, and the top ten sat between 57.6% and 70.0%. Most vendors in that test advertise something near 99%.
Both figures can be true at once. A vendor figure answers a narrow question: of the addresses we returned a verdict on, how many were right. It is calculated after the catch-all domains and the servers that refuse to answer have left the denominator, and those are exactly the addresses that were hard.
The trouble is what that metric rewards. Resolve ambiguous addresses to valid rather than labeling them, and accuracy goes up while your bounce rate goes up too. You'd watch the published number improve as the product gets worse. The accuracy argument in full walks through the arithmetic.
So we report two
Coverage is the share of your list we reached a defensible verdict on. Accuracy is how often those verdicts held. Each one alone is gameable in opposite directions, and moving both at once is the only honest kind of progress.
The component that renders them will not accept one without the other. That sounds like a small engineering decision, and it is the whole company.
Where the hard addresses live
The missing denominator is large. On one 10,000-address B2B benchmark, about 28% of the list sat on catch-all domains, which answer 250 to every address you ask about. Yahoo and AOL do the same on purpose, to stop anyone enumerating their users, and bounce the bad ones later. Gmail and Microsoft 365 block probes that come from cloud IP ranges.
A greylisting server returns a 4xx to every first attempt by design, so a verifier that asks once misreads it. That's how receiving servers protect themselves, and it holds for every verifier. On domains that respond honestly, a careful SMTP check can be right between 95% and 98% of the time.
ZapBounce labels each of those cases with its own result, so you see what reached a verdict and what did not. You pay for the verdicts and nothing else.
What we put in writing
We run our own SMTP check over port 25, not a wrapper around another company's verification API. We open the connection, ask the server about the address, and close before the DATA command, so no message ever reaches the person you're checking. The step-by-step check shows each stage.
Some phrases will never appear on this site: 100% accurate, guaranteed inbox, spam trap removal. A pristine spam trap looks exactly like a working mailbox at the protocol level, so anyone promising to remove them is selling a probability. When we flag a likely recycled trap by heuristic, the result says it is a heuristic flag.
The benchmark method is published in full, so you can hold every number we report to a fixed standard.
What you pay for, and what you never pay for
1,000 checks cost $5 pay as you go, with no minimum purchase. The ladder runs to $949 for 1,000,000. If you verify every month, a monthly plan costs 15% less for the same credits, from $4 a month, and unused credits roll over while the plan is active. Every tier is on the pricing page.
A credit buys one definite answer: valid, invalid or catch-all. An unknown costs nothing, and a duplicate in the same upload costs nothing. Credits never expire, so a list you clean twice a year keeps its value between cleans.
Every account gets 100 free checks a month, every month, with no card. That's enough to run a real sample through us beside any other verifier and count what comes back unresolved.
Who runs ZapBounce
ZapBounce is operated by Hashlogics, a US LLC, with its team in Lahore. ZapBounce is not affiliated with ZeroBounce. If you want to see how the two differ on price and billing, read ZapBounce vs ZeroBounce.
Your lists are hosted in the United States, and ZapBounce never sells uploaded addresses or adds them to a shared database. The security page and the data processing terms cover retention, erasure and the sub-processors by name. You can reach us through the contact page.
Test the claim on your own list
100 free checks a month. Count what comes back unresolved.