Benchmark · 2024

Email verifier tools: the most complete benchmark & ranking

The 11 most popular email verifier services, put to the test on 10,000 real emails.

You are looking for the best email verification software? You tried a couple of them, and you still got 5% of your emails that bounce (or more)? Read on, because we have (surprising) facts for you.

First, a bit of backstory: at FullEnrich, we verify millions of emails per month. But we have always been disappointed by the various email verification tools we tried. They all say "99% delivery guaranteed". But when you try it, your emails bounce 5% of the time (or more).

So in 2024 we started our hunt to find the best email verification software. We looked for a trusted benchmark source, but most email-verifier comparison articles are written just to rank on Google. So we decided to spend $2,000 to scientifically test every email verification software — and the results were (very) surprising.

In this article, we are going to see:

Our methodology
The (surprising) results
Why most email verifiers (kinda) suck
How to get a 1% bounce rate by stacking email verifiers
Conclusion

Testing methodology: 10,000 emails

To ensure unbiased results, we built a list of contacts spanning a wide range of profiles.

25 different countries (US, France, UK, India, Brazil, Canada, Israel, etc.)

5 different company sizes (1-9, 10-99, 100-999, 1,000-9,999, 10,000+)

30 different job titles (Sales, Lawyer, Marketing, Executive, Health Professional, etc.)

Various other details (tenure in company, with/without a LinkedIn profile, etc.)

To find the emails of these contacts, we used a mix of 10 different email finders (Hunter.io, Apollo, etc.) — all of them part of FullEnrich. We generated a list of 10,000 emails this way, then tested them by actually sending emails to these addresses to see whether they bounced.

10,000 test emails at a 19.5% base bounce rate: 8,048 deliverable and 1,952 undeliverable. We measured real deliverability by sending each email and tracking whether it landed in the mailbox or bounced.

11 email verifiers compared: facts & results

To compare email verification services, we used three criteria.

1

Real bounce rate on "valid" emails — and how many are deemed "valid"

This is the most important criterion. If you have a list of 1,000 emails but only 50 are deemed valid, even with a 0% bounce rate you only have 50 usable emails. Sometimes it is better to accept a higher bounce rate if it significantly increases the number of usable emails.

2

How many "invalid" emails are identified, and the rate of false positives

Invalid emails can be removed from a list without a second thought. However, if half of the "invalid" emails are actually valid, you have potentially discarded half of your usable emails.

3

Bounce rate if we send to "valid" + "catch-all"

Some industries have higher proportions of catch-all emails than others. If only valid emails are used, the list might be too small — so it is useful to look at the overall bounce rate in this scenario.

Here is the list of email verifier tools we tested:

Neverbounce
Zerobounce
Emailable
EmailListVerify
MillionVerifier
Debounce
Icypeas
Bounceless
Captain Verify
UseBouncer
Clearout

Overall ranking

Since some providers are better in certain areas but not in all areas, this ranking is not absolute and tries to consider different factors. If you only care about one factor — like the bounce rate for "valid" emails — you can check the charts below.

1 EmailListVerify
Best all-round
1 Icypeas
Strictest verifier
3 Bounceless
4 Neverbounce
5 Zerobounce
6 Debounce
7 Emailable
8 UseBouncer
9 Clearout
10 MillionVerifier
11 CaptainVerify

Bounce rate for "valid" emails

Lower is better. Icypeas is the clear winner; EmailListVerify also performs well. Household names like Emailable and Neverbounce sit noticeably higher.

Icypeas

3.17%

EmailListVerify

4.65%

Neverbounce

9.57%

Bounceless

9.64%

Debounce

9.88%

Zerobounce

10.11%

Emailable

10.43%

UseBouncer

11.18%

MillionVerifier

12.29%

Clearout

12.66%

CaptainVerify

13.01%

Total deliverable "valid" emails

Actually deliverable versus "false valid" that bounced.

Deliverable Bounced (false "valid")

Zerobounce

4,767

UseBouncer

4,757

Debounce

4,718

Bounceless

4,660

EmailListVerify

4,617

Emailable

4,575

Neverbounce

4,235

MillionVerifier

4,024

Clearout

3,953

CaptainVerify

3,940

Icypeas

3,848

Analysis on 10,000 emails by FullEnrich.

While Icypeas had a significantly lower bounce rate compared to other verifiers, it had the lowest number of "valid" emails found. Zerobounce found 23% more deliverable "valid" emails than Icypeas. EmailListVerify was the second best in terms of bounce-rate metrics and was also very close to the top position in the number of deliverable "valid" emails found, despite being in 6th position.

True "invalid" emails identified

Total "invalid" emails: those that actually bounced versus false "invalid" that were really deliverable.

"Invalid" that bounced False "invalid" (deliverable)

EmailListVerify

1,011

Clearout

539

CaptainVerify

511

Bounceless

481

MillionVerifier

479

Emailable

478

Debounce

431

UseBouncer

423

Zerobounce

408

Icypeas

224

Neverbounce

172

Analysis on 10,000 emails by FullEnrich.

EmailListVerify dominates every other email verifier on this criterion. UseBouncer is the most precise in its "invalid" categorization, with around 1% false positives — 10 times better than EmailListVerify. However, the sheer number of invalid emails found by EmailListVerify more than compensates for its slight lack of precision (around 10% false positives).

Bounce rate on "valid" + "catch-all"

Lower is better.

Icypeas

10.25%

EmailListVerify

10.50%

Neverbounce

12.56%

Bounceless

12.84%

Emailable

13.27%

Debounce

15.47%

MillionVerifier

15.56%

Clearout

15.63%

Zerobounce

15.70%

CaptainVerify

15.87%

While Icypeas is the winner here, EmailListVerify is very close. However, in the "valid" + "catch-all" category, Icypeas found 6,818 emails while EmailListVerify found 8,873. Even though Icypeas has a slightly lower bounce rate (by 0.20%), EmailListVerify lets you send 30% more emails. I would choose EmailListVerify over Icypeas every day.

Details for each metric

Provider	Total "valid"	Deliverable "valid"	Bounced "valid"	Bounce rate on valid	Total "invalid"	False positives	True invalid	Invalid error rate	Valid + catch-all bounce rate
Bounceless	5,157	4,660	497	9.64%	576	95	481	16.49%	12.84%
CaptainVerify	4,529	3,940	589	13.01%	735	224	511	30.48%	15.87%
Clearout	4,526	3,953	573	12.66%	773	234	539	30.27%	15.63%
Debounce	5,235	4,718	517	9.88%	472	41	431	8.69%	15.47%
Emailable	5,108	4,575	533	10.43%	617	139	478	22.53%	13.27%
EmailListVerify	4,842	4,617	225	4.65%	1,118	107	1,011	9.57%	10.50%
Icypeas	3,974	3,848	126	3.17%	375	151	224	40.27%	10.25%
MillionVerifier	4,588	4,024	564	12.29%	505	26	479	5.15%	15.56%
Neverbounce	4,683	4,235	448	9.57%	247	75	172	30.36%	12.56%
UseBouncer	5,356	4,757	599	11.18%	427	4	423	0.94%	—
Zerobounce	5,303	4,767	536	10.11%	449	41	408	9.13%	15.70%

Download the full file with emails & status for each provider.

Download

How to get a 1% bounce rate

Stack email verification services so their strengths complement each other.

It turns out that some verifiers complement each other. By combining the strengths of each, you can achieve "valid" emails with bounce rates on the order of 1%. Three verification services stack particularly well:

Icypeas

Lowest bounce rate on valid emails.

EmailListVerify

Finds the highest number of invalid emails.

Neverbounce

Complements the other two surprisingly well.

Here is what the result looks like on a chart:

Stack up to 3 email verifiers to drop bounce rate to 1%

Base bounce rate

19%

Icypeas

3.17%

Icypeas + EmailListVerify

2.12%

Icypeas + EmailListVerify + Neverbounce

1.3%

Analysis on 10,000 emails by FullEnrich.

FullEnrich: triple email verification included for free with every lead enrichment

In this article, we've taken a deep dive into the world of email verification tools, and frankly, the results were not quite what we expected. While each tool promises near-perfect accuracy, our exhaustive testing showed that a 5% bounce rate is still a common issue.

If you're looking for emails and phone numbers of people, you should check out FullEnrich.

We are not just another email and phone finder. We aggregate contact information from 15 different data sources to find your lead's contact details. If we cannot find someone's contact information, nobody else can.

And of course, now you know how we ensure our emails are as valid as possible.