How accurate is ListBouncer? We tested it.
We sent real emails to prove which addresses work and which bounce, then ran the same addresses through ListBouncer. Here's every result, including the parts nobody can check.
- 100%
- accuracy on checkable addresses (134 of 134)
- 0
- bad addresses marked Safe
- 0
- real inboxes marked Will bounce
154 addresses checked. Yahoo, Outlook, Hotmail and AOL are counted separately below, because those providers limit what anyone can check.
What happened, group by group
What the test email proved, next to what ListBouncer said.
Real inboxes
4 addresses
ProofTest email sent to all 4. None bounced.
ListBouncer3 Safe. The fourth, a support@ address, was flagged as a shared inbox, which is what we do with every info@ or support@.
MatchedFake mailboxes on real providers
60 addresses
ProofRandom names on Gmail, iCloud, Proton, Fastmail, Hey and our own domain. All 60 bounced.
ListBouncer60 of 60 Will bounce.
MatchedDomains that can't receive mail
25 addresses
ProofMade-up domains, example.com, example.org and .invalid addresses. All 25 bounced.
ListBouncer15 Will bounce. 10 example.com and example.org addresses were flagged Risky as made-up test addresses. All 25 were kept out of the clean list.
MatchedTypos of big providers
20 addresses
Proofgmial.com, hotmial.com, yahooo.com and similar. Wrong mailbox by definition, so we didn't email them.
ListBouncer20 of 20 caught: 19 as typos with the fix suggested, 1 (gmai.com) as a throwaway domain.
MatchedDisposable addresses
25 addresses
ProofMailinator, Guerrilla Mail, 10 Minute Mail, YOPmail and TrashMail. Throwaway by definition.
ListBouncer25 of 25 Disposable.
MatchedYahoo, Outlook, Hotmail and AOL
20 addresses
Proof1 real Yahoo inbox (delivered) and 19 fake addresses. 18 of the fakes bounced; 1 Outlook address never answered either way.
ListBouncer8 of the 10 fake Outlook and Hotmail addresses were caught as having no mailbox. Everything else went to Major provider. None were marked Safe.
Matched, with limits
Known answers.
Real email.
A verifier can only be judged against addresses where the right answer is proven. So we proved them first.
No customer data was used. Every address was an inbox we own or one we made up for the test.
Build a test set with known answers
154 addresses in six groups: real inboxes we own, random names that can't exist, dead domains, typos, throwaway services, and the big consumer providers.
Prove the answers by sending real email
We emailed 109 of them from an ordinary Gmail account, never from ListBouncer's own sending domain, and recorded every bounce. Typos and throwaway addresses are wrong by definition, so they weren't emailed.
Run them through ListBouncer like a customer
The same addresses were uploaded as a normal CSV to a normal account, paid with normal credits. No special settings, no second tries.
Compare, and publish all of it
Every result is counted here, including the addresses no verifier can check.
The honest limits
Every verifier has them. Here are ours, so you know what you're buying.
Yahoo and AOL can't be checked by anyone.
They don't let anyone confirm whether a single mailbox exists, so those addresses always go to Major provider. That's not a ListBouncer gap; it's how those providers work.
Outlook and Hotmail are partly checkable.
Microsoft sometimes says a mailbox doesn't exist. When it does, we mark it Will bounce. When it doesn't answer, the address stays in Major provider instead of getting a guess.
Business mail servers vary.
Some company mail servers block every check, so their addresses come back Unknown. None came back Unknown in this test, but it happens on real lists, and Unknown is the honest answer when it does.
About the test
01How accurate is ListBouncer?+
In our November 2026 test, ListBouncer got 100% of checkable addresses right: 134 of 134. All 4 real inboxes were kept, and all 130 fake, dead, typo and throwaway addresses were caught. Yahoo, Outlook, Hotmail and AOL are counted separately, because those providers limit what anyone can check.
02What counts as a checkable address?+
Any address on a provider that lets mail servers answer whether a mailbox exists, plus addresses we can rule out without asking, like dead domains, typos and throwaway services. Yahoo and AOL never answer, and Outlook and Hotmail only sometimes do, so they're reported separately.
03Can ListBouncer verify Yahoo, Outlook, Hotmail or AOL addresses?+
Not fully. Yahoo and AOL don't let anyone confirm a single mailbox, so those addresses go to their own Major provider group. Microsoft sometimes confirms that an Outlook or Hotmail mailbox doesn't exist, and when it does we mark it Will bounce.
04How did you prove which addresses were real?+
We sent a short test email to 109 of the addresses from an ordinary Gmail account and recorded which ones bounced. Typos and throwaway addresses weren't emailed, because they're wrong by definition.
05Did you use customer data for this test?+
No. Every address in the test was either an inbox we own or one we made up for the test.
06Will you run the test again?+
Yes, from time to time, especially after changes to how ListBouncer checks addresses. Each run will be dated on this page.
Test it on your own list.
Every account starts with 100 free credits. Or try a handful of addresses on the free checker, no sign-up needed.