We picked 10 emails across every major validation category — valid, invalid, disposable, role-based, catch-all, typo, gibberish, fake mailbox, and spam trap — then ran both services side-by-side.
Same emails. Same 60-second window. Honest results.
Last updated April 11, 2026
Same accuracy. More transparent. 89% less.
| # | Test Type | MailSentry | Kickbox | Result | |
|---|---|---|---|---|---|
| 1 | ceo@apple.com | Valid corporate | ValidScore 90 | Deliverable (role) | TIE |
| 2 | thaothuc***@gmail.com | Valid Gmail | ValidScore 100 | Deliverable | TIE |
| 3 | test@guerrillamail.com | Disposable | Invalid (disposable)Score 25 | Undeliverable (disposable) | TIE |
| 4 | info@google.com | Role-based | Caution (role-based)Score 85 | Risky (role) | TIE |
| 5 | john@gmial.com | Typo | Invalid (typo → gmail.com)Score 0 | Undeliverable (did_you_mean) | TIE |
| 6 | hello@zapier.com | Catch-all | Caution (role-based)Score 85 | Risky (accept_all) | TIE |
| 7 | not-an-email | Bad syntax | Invalid (bad syntax)Score 0 | Undeliverable (invalid_email) | TIE |
| 8 | randomxyz123abc@microsoft.com | Fake mailbox | Risky (SMTP invalid)Score 50 | Unknown (no_connect) | TIE |
| 9 | asdfjkl@yahoo.com | Gibberish | Invalid (gibberish)Score 25 | Undeliverable (rejected_email) | MS WINS |
| 10 | test@mailinator.com | Spam trap | Invalid (disposable)Score 25 | Undeliverable (disposable) | TIE |
Test #9 (asdfjkl@yahoo.com) is where the two services diverge. Kickbox returns undeliverable via SMTP mailbox lookup — correct, but without identifying why. MailSentry flags it specifically as gibberish using a bigram/vowel-ratio algorithm, so you know the pattern even before SMTP runs.
Why it matters: Yahoo and Gmail happen to reject unknown mailboxes honestly, so Kickbox lands this one. For providers that accept all and silently drop — Microsoft, many corporate domains — SMTP alone doesn't help, and Kickbox would return "risky" or "unknown". MailSentry's gibberish detector catches these patterns before SMTP is even needed.
MailSentry gives you 1,000 free validations every month, renewing automatically. Kickbox offers 100 free credits as a one-time trial — use them up and you're paying. If you validate small lists regularly, MailSentry covers you indefinitely.
MailSentry flagged asdfjkl@yahoo.com as gibberish — a check Kickbox doesn't offer. Kickbox only catches it because Yahoo's SMTP reports the mailbox as missing. For domains that don't respond honestly to SMTP, MailSentry still catches the pattern.
Same accuracy, fraction of the price. Kickbox charges $80 for 10,000 validations. MailSentry charges $9/month for the same volume — and it's a monthly subscription, not pay-as-you-go credits that you have to top up.
| MailSentry | Kickbox | |
|---|---|---|
| Free tier | 1,000 / month (ongoing) | 100 credits (one-time) |
| 1,000 checks | Free | $10 |
| 10,000 checks | $9/mo | $80 |
| 50,000 checks | $29/mo | $400 |
| 100,000 checks | $79/mo | $800 |
| 500,000 checks | $199/mo | $2,500 |
| Gibberish detection | Included | Not available |
| Risk scoring | 0-100 scale | Sendex (0-1) |
| Billing model | Monthly subscription | Pay-as-you-go credits |
| Bulk validation | Included | Included |
| Email finder | Included | Included |
MailSentry prices are monthly subscription plans. Kickbox prices are published pay-as-you-go rates. Both as of April 2026.
1,000 free checks every month. No credit card required.
Try MailSentry FreeTest conducted April 11, 2026. Both services called on the same 10 emails within a 60-second window. MailSentry was tested via the production API at api.mailsentry.dev/v1/verify. Kickbox was tested via its bulk verification dashboard. Full methodology.