TL;DR
- Judge a verifier on catch-all labelling, unknown refunds, credit expiry and price per email, then on integrations.
- On published numbers, Mail Exchange is the cheapest of the big names at 5K and 100K, with refunds for unknowns and credits that never expire.
- It has no native connectors, the API is in early access, and the widget is on the roadmap. If you need those, pick one of the others.
1. Catch-all handling
Catch-alls are the hardest part of a B2B list. In Hunter's published test (checked 2026-10-17), accept-all addresses bounced 27% of the time against 1% for valid ones. What matters is that the verifier labels them rather than calling them valid, so you can route them. ZeroBounce has a catch-all status, NeverBounce has a catchall result, and Emailable uses a low_deliverability reason. Mail Exchange labels them risky: catch-all, separate from role and disposable. Guide: should you send to catch-all emails?
2. Unknown results and refunds
An unknown is an address the mail server would not answer for. You should not pay for it. Emailable, Kickbox, ZeroBounce and Mail Exchange do not charge for unknowns. NeverBounce's policy is not clearly stated on its site, so ask before you buy. (Competitor pages claim they are charged, but we couldn't confirm it.)
3. Credit expiry
Emailable and Mail Exchange credits never expire. NeverBounce pay-as-you-go credits expire 12 months after purchase. For ZeroBounce and Kickbox we did not confirm expiry terms, so read them before you buy a large pack. Uneven cold-email volume makes expiry matter.
4. Price per email at 5K and 100K
| Verifier (pay as you go) | 5,000 emails | 100,000 emails |
|---|---|---|
| Mail Exchange | $29 ($0.0058) | $299 ($0.0030) |
| Emailable | $38 ($0.0076) | $420 ($0.0042) |
| NeverBounce | $40 ($0.0080) | $400 ($0.0040) |
| Kickbox | $40 ($0.0080) | $500 ($0.0050) |
| ZeroBounce | $69 ($0.0138) | $649 ($0.0065) |
| BriteVerify | No public pricing; sales contact required | |
From each vendor's pricing page, checked 2026-10-17: Emailable, NeverBounce, Kickbox, ZeroBounce. NeverBounce also sells monthly Growth plans that cost less than ours from about 50K emails a month; this table compares one-off packs only. More in verification pricing compared.
5. Speed
We have no published speed figure for any vendor, so we won't rank on it. Check it yourself with your own file. For Mail Exchange, most single checks answer in a few seconds, and slow mail servers return a pending result you fetch later. Bulk jobs accept up to 100,000 addresses per call.
6. Integrations and API
Emailable and Kickbox list HubSpot, Mailchimp, Klaviyo, Salesforce and Zapier; NeverBounce lists 80+ integrations; ZeroBounce has a long list too. All have APIs. Most cold-email sequencers have no first-party link to these verifiers, so the CSV workflow is common anyway.
How to choose
- Verifying cold-email lists in CSV batches, uneven volume: price, refunds and no expiry point to Mail Exchange or Emailable. See vs Emailable.
- Need a bundle (finder, warmup) or many native integrations: look at ZeroBounce, NeverBounce or Emailable. See vs ZeroBounce.
- Unsure: verify the same 500 addresses in two tools and compare to your real bounces. Start with the 3-day free trial at Mail Exchange.