Email verification statistics
The most cited email verification statistics, each traced to its primary source. Hunter's test of 15 verifiers on 3,000 real business addresses (3 November 2025) measured 31.2% to 70.0% accuracy. Hunter found 5.5% of verified addresses degraded within 8 weeks (4 November 2025). ZeroBounce reports a 1.75% unknown rate for 2025, and Amazon SES recommends keeping bounces under 2%.
The short version
- Vendor accuracy claims sit at 99% and up; Hunter's benchmark counting every address put 15 verifiers between 31.2% and 70.0%.
- Lists decay fast: Hunter measured 5.5% of verified addresses going bad within 8 weeks.
- Amazon SES recommends a bounce rate under 2% and says 10% or more might pause your sending.
- Published turnaround for a 100,000-address list runs from minutes at Emailable to under 2 hours at DeBounce.
Where these numbers come from
- Every figure below comes from a primary source: the vendor, the mailbox provider or the study's author. Each carries the date it was published or read.
- Figures were read on 2026-09-24, except vendor accuracy claims, read on 2026-09-18.
- Numbers that circulate without a traceable primary source were left out, however often they're quoted.
- Vendors that show no readable figures on their own pages, such as NeverBounce, appear with no number.
Accuracy: claims of 99% and a measured 31.2% to 70.0%
Vendors publish accuracy figures above 99%. Those count only the addresses each tool gave a firm verdict on, so unknowns and catch-alls leave the sum first.
Hunter's benchmark kept every address in the count. It scored 15 verifiers on 3,000 real business addresses, and its own tool came top at 70.0%. The full argument is in our report on whether benchmarks are trustworthy.
| Statistic | Figure | Source | Date |
|---|---|---|---|
| ZeroBounce accuracy claim | 99.6% | ZeroBounce, about its own tool | Read 2026-09-18 |
| Clearout accuracy claim | 99.73% | Clearout, about its own tool | Read 2026-09-18 |
| Reoon accuracy claim | Over 99% | Reoon, about its own tool | Read 2026-09-18 |
| Measured accuracy, 15 verifiers | 31.2% to 70.0% | Hunter benchmark, 3,000 addresses | 3 Nov 2025 |
| Measured accuracy, top ten | 57.6% to 70.0% | Hunter benchmark, 3,000 addresses | 3 Nov 2025 |
Bouncer and Emailable publish no accuracy percentage. Hunter's benchmark was read on 2026-09-24.
Unknown and valid rates reported by vendors
An unknown rate tells you how often a verifier couldn't reach a verdict. ZeroBounce reports its 2025 unknown rate as 1.75% and says unknowns are not charged. Bouncer states under 2% unknown results.
ZeroBounce also reports that 89% of the emails it verified were classified valid. Read that as a fact about the lists its customers upload, not about lists in general. Your own share depends on where the list came from and how old it is.
| Statistic | Figure | Source | Read |
|---|---|---|---|
| Unknown rate, 2025 | 1.75% | ZeroBounce facts page | 2026-09-24 |
| Emails classified valid | 89% | ZeroBounce facts page | 2026-09-24 |
| Unknown results | Under 2% | Bouncer homepage | 2026-09-24 |
Each figure is the vendor's statement about its own results, read on its own site. None of them is an independent measurement.
List decay: 5.5% of verified addresses go bad in 8 weeks
Hunter re-checked addresses it had already verified and found 5.5% had degraded within 8 weeks. 2.3% had become invalid, and 3.2% now sat on catch-all domains, published on 4 November 2025.
Eight weeks is short. A list you cleaned before a quarterly campaign has already shifted by the time the next one goes out. Our answer on how often to clean your list turns that into a schedule.
Bounce and complaint limits set by mailbox providers
Amazon SES publishes hard numbers. It recommends a bounce rate under 2%, reviews accounts at 5% and says it might pause sending at 10% or more. For complaints, it recommends staying under 0.1% and might pause at 0.5%.
Google's sender guidelines ask you to keep the spam rate in Postmaster Tools below 0.10%, and to avoid ever reaching 0.30% or higher. Mailchimp publishes no figure. It says suspensions are automatic when a single send exceeds industry thresholds.
| Provider | Recommended | Review or warning | Pause or block |
|---|---|---|---|
| Amazon SES, bounces | Under 2% | 5% or more | 10% or more |
| Amazon SES, complaints | Under 0.1% | 0.1% or more | 0.5% or more |
| Google, spam rate | Under 0.10% | Never reach 0.30% | Not stated |
Read on the Amazon SES enforcement FAQ and Google's email sender guidelines on 2026-09-24.
Turnaround: minutes to hours for 100,000 addresses
Published speeds for a single-pass bulk check vary widely. Emailable states 250,000 addresses in under 7 minutes. ZeroBounce quotes about 45 to 60 minutes per 100,000, and DeBounce under 2 hours for 100,000.
Reoon quotes 8 to 12 minutes for 10,000 mixed-quality addresses. Deep catch-all passes take far longer: Scrubby's deep check gives final results after 72 hours, because it waits on real delivery.
Billing: 8 of 13 vendors don't charge for unknowns
Of 13 vendors whose billing rules could be read on their own sites in September 2026, 8 state that unknown results are free. Every vendor that states a catch-all rule charges for catch-all results.
On expiry, Kickbox credits expire one year from purchase and Hunter's can be used for 12 months. Most other vendors say pay-as-you-go credits never expire. The credit expiry and unknown billing report lists every vendor's rule.
ZapBounce never bills an unknown or a duplicate, and its credits never expire. Packs start at $5 for 1,000 checks, with 100 free checks every month and no card. The pricing page has every tier.
Sources
Questions people ask
How accurate is email verification?
Vendors claim over 99%, counted on the addresses they gave a firm verdict on. Hunter's benchmark of 3 November 2025 counted every one of 3,000 real business addresses and measured 15 verifiers at 31.2% to 70.0%. Compare coverage beside accuracy to see the full picture.
How fast do email lists decay?
Hunter found 5.5% of verified addresses had degraded within 8 weeks, published on 4 November 2025. 2.3% became invalid and 3.2% moved to catch-all domains. That pace means a list cleaned once a quarter drifts noticeably between campaigns.
What bounce rate is too high?
Amazon SES recommends staying under 2%, reviews accounts at 5% and might pause sending at 10% or more, read in September 2026. Google asks senders to keep the spam rate below 0.10% and never reach 0.30%.
What percentage of verification results come back unknown?
ZeroBounce reports a 1.75% unknown rate for 2025, and Bouncer states under 2%, both read in September 2026. The share on your own list depends on its mix of catch-all, Yahoo and Microsoft addresses.
Check your own list's coverage
100 free checks a month, no card. Every result comes back as valid, invalid, catch-all or unknown, and unknowns are never billed.