ZeroBounce review (2026): fast, accurate, and no fakes passed

What is ZeroBounce?

ZeroBounce checks whether an email address will accept mail before you send to it. Liviu Tanase founded it in 2013 in Santa Barbara, and it says more than 650,000 customers use it, from people cleaning a newsletter list to outbound teams checking every address before a sequence starts.

You can upload a list or call one endpoint per address. Each check returns one of seven statuses (valid, invalid, catch-all, unknown, spamtrap, abuse, or do not mail) with a sub-status that says why, such as mailbox_not_found or greylisted. Around that, ZeroBounce has built a deliverability suite: an email finder, warmup, DMARC and blacklist monitoring, and inbox placement tests.

How it did in our test

We ran 100 labelled addresses through four verifiers. Fifty were real: pipe0 users who had signed in with Google in the previous 45 days, 30 on work domains and 20 on Gmail. Fifty were fake: random mailboxes at Gmail, Outlook, and well-known company domains, and addresses at domains that don't exist.

ZeroBounce got 96 of them right. It confirmed 47 of the 50 real addresses and caught 49 of the 50 fakes, and it passed none of the fakes as valid. If you had sent only to the addresses it called valid, nothing in this test would have bounced.

Every verifier handled the easy cases perfectly: real Gmail addresses, random Gmail and Outlook mailboxes, and domains with no mail server. The difference was entirely on work domains. On 30 real work addresses, ZeroBounce gave a definite answer on 29. MillionVerifier called 18 of the same 30 catch-all, which in practice means "send at your own risk".

ZeroBounce called two real addresses invalid. One of those, every verifier rejected, which suggests the address stopped existing after the user's last sign-in rather than an error by ZeroBounce.

What it costs

Pay-as-you-go packs start at $39 for 2,000 checks, almost 2 cents each, and fall to about 0.3 cents a check at a million or more. ZeroBounce ONE, the subscription, costs $79 a month billed annually for 10,000 checks a month plus the deliverability tools. There are 100 free checks a month for a business email address.

That is several times the price of budget verifiers: 10,000 checks cost $129 at ZeroBounce and $39 at MillionVerifier. Unknown results are free, but catch-all results are billed. One change to know about: for accounts created after June 1, 2026, credits expire two years after the last purchase unless a subscription is active.

ZeroBounce for developers and agents

The API has a real-time endpoint, a batch endpoint for 100 addresses per request, and a bulk file API, with SDKs in 13 languages and a limit of 80,000 requests per 10 seconds. It answered in a median of 0.3 seconds in our test, the fastest of the four. ZeroBounce also publishes an official, open-source MCP server, so an agent in Claude, Cursor, or VS Code can verify an address before it writes to a CRM or a sequence.

For companies with security reviews, ZeroBounce says it holds SOC 2 Type 2, ISO 27001, and HIPAA certifications, and it runs its own data centers in Frankfurt and New York.

ZeroBounce and pipe0

We buy verification from ZeroBounce, and pipe0 offers it as a pipe you can add to a sheet next to email finding. We chose it for accuracy on work domains, which is where outbound lists live, and this benchmark is the reason it stays.

Who should buy ZeroBounce

Buy ZeroBounce if you send to work addresses and a bounce costs you more than a check does: cold outbound, sales sequences, anything on a domain you care about. Its answers on catch-all-looking work domains are the reason to pay the premium.

Look elsewhere if you verify very large consumer lists where price per check decides, or if you buy credits once and use them over years. Then MillionVerifier costs a fraction and handles consumer addresses just as well.