Do Email Verifiers Charge for Unknown, Catch-All and Duplicate Results?
The price per credit is only part of what a verifier costs. Vendors differ on three things that change the real bill: whether unknown results use a credit, whether catch-all results do, and whether duplicates do. Several vendors refund unknowns. Catch-alls are usually charged. Duplicates vary. Credit expiry varies too. Check all four before you buy a large pack.
Facts below come from each vendor's own pricing page, FAQ or terms as recorded in our vendor data in October 2026. Terms change, so treat this as a list of questions to confirm, not a final answer.
Why this matters on B2B lists
On a clean consumer list, almost every row comes back valid or invalid, and the charging rules barely matter. On a B2B list they matter a lot. Many business domains accept every address, so a B2B list often has a large catch-all share. If you pay full price for every catch-all row, a large share of your spend buys results you cannot act on with confidence.
Unknown results
An unknown result means the verifier could not get an answer: the server timed out, refused or gave nothing useful.
| Vendor | Unknown results |
|---|---|
| ZeroBounce | Not charged |
| Kickbox | Refunded as credits |
| Reoon | Refunded automatically when the task finishes |
| Emailable | Credits returned when a list finishes |
| Hunter | Do not consume credits |
| Others | Check current terms |
This is a fair practice and many vendors follow it. If a vendor charges for unknowns, ask what share of a typical B2B list comes back unknown, and price that in.
Catch-all results
A catch-all result means the domain accepts every address, so the mailbox cannot be confirmed. Most vendors treat this as a completed check and charge it.
| Vendor | Catch-all results |
|---|---|
| Reoon | Charged; its FAQ counts a catch-all as a successful verification |
| DeBounce | Standard result charged; a deeper catch-all validation is sold at 10 credits |
| Most others | Treated as a completed check; confirm with the vendor |
That is defensible. The verifier did the work. But it means the cost per usable lead is higher on a B2B list than the headline price suggests.
There is a second question: how is the catch-all result labelled? Some tools return it as its own status; some fold accept-all into a "valid" or "deliverable" bucket. If it is folded in, the valid rate looks higher and the bounce rate after sending is higher too. SimpleVerifier never marks catch-alls valid; it grades each one higher, medium or lower likelihood. See catch-all email verification.
Duplicates
| Vendor | Duplicates in one list |
|---|---|
| DeBounce | Removed for free |
| Emailable | Credits returned |
| Others | May be charged; check |
Easiest fix: remove duplicates before upload. The duplicate email remover does it in the browser.
Re-checks of the same address
This is the biggest hidden cost for cold emailers, who re-verify leads before campaigns.
| Vendor | Re-checking an address verified before |
|---|---|
| Credit vendors in general | Charged again each pass |
| NeverBounce Growth | Only new, unique emails are billed, according to NeverBounce |
| SimpleVerifier | Confirmed results cached 14 days; Pro, Business and Agency have no per-email charge under fair use |
NeverBounce's Growth rule is worth noting: if you sync the same lists repeatedly, it does not bill addresses it has already seen.
Credit expiry
| Vendor | Credit expiry |
|---|---|
| NeverBounce | Pay-as-you-go credits expire 12 months after purchase |
| Kickbox | Credits expire one year from purchase, per its terms |
| ZeroBounce | Its page says expiry rules may apply depending on account or purchase date |
| Reoon | Instant credits never expire |
| MillionVerifier | Never expire |
| Bouncer | Never expire, on packs and subscription |
| DeBounce | Pay-as-you-go credits never expire |
| Emailable | Never expire; subscription credits roll over |
Expiry turns a discount into a loss if a campaign slips. Buy packs sized for what you will use inside the expiry window.
What SimpleVerifier charges for
To be clear about our own rules:
| Plan | How it is charged |
|---|---|
| Starter ($9, 2,500 a month) | Monthly allowance; duplicates and addresses we cannot check do not count; unused emails do not roll over |
| Pro ($39) | No per-email charge under fair use: the first 100,000 checks a month at full speed, then slower, never cut off |
| Business ($99) and Agency ($249) | The first 300,000 and 750,000 checks a month at full speed, then slower, never cut off |
API calls are counted separately on Pro, Business and Agency. Details are on the pricing page.
Questions to ask any vendor
- Are unknown results charged or refunded?
- Are catch-all results charged, and how are they labelled?
- Are duplicates in one upload charged?
- Is a re-check of an address verified last month charged again?
- Do credits expire, and when?
- Is there an extra charge for deeper catch-all checks?
Our questions to ask before buying an email verifier covers accuracy and support questions too.
Worked example (illustrative)
A team verifies 20,000 B2B leads with 600 duplicates, and the results include 5,000 catch-all and 1,000 unknown rows.
| Charging rules | Credits used |
|---|---|
| Everything charged | 20,000 |
| Duplicates free | 19,400 |
| Duplicates and unknowns free | 18,400 |
The difference is 8% of the bill on one list, more if you repeat it monthly.
Check before you commit
Ask the questions above, then run a sample of your own list. The first 100 checks on SimpleVerifier are free with a Google sign-in on the verify page.
Common questions
Do email verifiers charge for unknown results?
It depends on the vendor. ZeroBounce, Kickbox, Reoon, Emailable and Hunter say unknown results are not charged or are refunded. Others may charge them. Check each vendor's current terms before buying a large pack.
Do email verifiers charge for catch-all results?
Usually yes. A catch-all result is a completed check: the server answered, it just accepts every address. Reoon's FAQ counts it as a successful, charged verification. Some vendors sell an extra catch-all check at a higher credit cost.
Do I pay for duplicate emails in my list?
At some vendors, no: DeBounce and Emailable say duplicates are free or refunded. At others they may be charged. Removing duplicates before upload avoids the question.
What does SimpleVerifier charge for?
On Starter, duplicates and addresses we cannot check do not count against the monthly allowance. Pro, Business and Agency have no per-email charge under fair use. Confirmed results are cached for 14 days, so overlapping re-checks return instantly.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.