Bouncer is the validator we respect most in this category. They are EU-headquartered, have a 4.8/5 G2 across 332 reviews, run a SOC 2 Type I audit (Type II in progress), and ship genuinely responsive support.
So if you are searching for a free Bouncer alternative, you probably are not looking because Bouncer is a bad product. You are looking because of price (Bouncer is paid-only, no recurring free tier) or because their per-check verdicts do not surface the SMTP reply, the MX record, or a confidence score the way you need them to.
MailCull is built for both. One flat $19/month price. Twenty plain-English checks per email with the SMTP reply, the MX record, and a confidence score on every verdict. And our free tier includes 100 deep-scan checks per month plus 1,000 deep-scan list rows per month — recurring, not one-time.
What MailCull does that Bouncer does not
The evidence chain on every verdict
Bouncer returns a verdict — deliverable, risky, undeliverable, unknown — with a category for some statuses (catch-all yes/no, role yes/no). Their dashboard shows aggregate signals but does not surface the SMTP reply or per-check confidence score.
MailCull returns the verdict plus a 20-code evidence chain. A real example for a corporate Microsoft 365 address:
[email protected] ✓ deliverable
─────────────────────────────────────────────────────────
syntax_valid Email format passed RFC 5321 validation
mx_found MX record: bigeuco-de.mail.protection.outlook.com
provider_microsoft Microsoft 365 protected tenant (EU region)
m365_http_enum Microsoft confirmed mailbox via GetCredentialType
m365_smtp_corroborated SMTP probe agreed: 250 OK on RCPT TO
tls_upgraded STARTTLS handshake completed
smtp_confirmed Server returned 250 2.1.5 OK
Confidence: 0.94 Source IP: probe-1.mailcull.ioWhen the verdict is risky, the difference matters most. Bouncer's "risky" tells you to be careful; MailCull's "risky" tells you exactly which signals contradicted each other and at what confidence.
Recurring free tier with the moat
Bouncer's free tier is 100 verifications, one-time, on signup. After that, every check is a paid credit.
MailCull's free tier is 100 deep-scan single-checks plus 1,000 deep-scan list rows, every month, recurring. Quick-scan (syntax + MX + typo + disposable) is unlimited. The deep-scan checks include the full evidence chain — same engine Pro customers run.
This means an SDR can validate their daily 30-50 highest-stakes outbound contacts indefinitely on Free, and an agency can clean a real 1,000-row test segment monthly without committing to a paid plan.
The Microsoft 365 corporate cascade with cross-check
Microsoft 365 hybrid tenants (banking, govt, large enterprise) are where most validators fail. Microsoft Exchange Online Protection (EOP) returns 250 OK for some non-existent mailboxes and 550 5.4.1 for some real mailboxes. A naive SMTP probe gets the wrong answer in both directions.
Bouncer handles M365 well for cloud-only tenants. They do not run the cross-check pattern that catches orphan-directory false-positives on hybrid tenants.
MailCull runs getuserrealm.srf → GetCredentialType → Autodiscover v1, then an SMTP cross-check at the end. When the cascade and SMTP disagree, we return risky with a m365_smtp_disagreed flag rather than a confidently wrong verdict.
Flat predictable pricing
Bouncer is credit-based — competitive but not flat. Per-credit pricing depends on the pack.
MailCull is $19/month flat for Pro (5,000 single-checks, 100,000 list rows), $49/month for Scale (25,000 single-checks, 500,000 list rows). No credits, no charge for unknowns, no surprise overages.
Where Bouncer is still the right answer
In the interest of fair framing:
EU data residency. Bouncer is headquartered in Poland, operates EU-only data centers, and has GDPR-native processes that go beyond the standard SCC compliance. If your procurement gates on data sovereignty, Bouncer is the right answer. MailCull is GDPR-compliant via SCCs but is not EU-headquartered.
G2 track record. 332 reviews at 4.8/5, built over years. We are newer with fewer reviews. If procurement weighs G2 maturity, that is a real Bouncer advantage today.
SOC 2 Type I in production. Bouncer's Type II is in progress (since 2023). MailCull's Type II audit is in progress as of 2026, projected complete by month 9. If you need Type II today, ZeroBounce or Kickbox are the right answers; if you need it within the year, we will be there.
Customer support velocity at scale. Bouncer's support team is well-staffed and fast. As a solo founder, our reply velocity today is competitive but not scaled.
Honest accuracy comparison
Bouncer claims 97%+ accuracy. Independent third-party tests in 2024-2025 land between 93% and 96% on mixed lists — closer to their claim than ZeroBounce or NeverBounce.
MailCull publishes 91-93% real-world accuracy on mixed lists, refreshed quarterly with full methodology at mailcull.io/methodology:
| Class | MailCull accuracy |
|---|---|
| Consumer (Gmail, Yahoo, Outlook with real local-parts) | ~95% |
| M365 cloud-only managed tenants | ~92% |
| M365 hybrid / federated | 85-90% |
| Catch-all corporate domains | ~80% |
| Mixed bulk lists (typical customer upload) | 91-93% |
The 2-3 percentage points where Bouncer edges MailCull on consumer Gmail/Yahoo accuracy is real. On B2B-heavy lists with significant Microsoft 365 corporate volume, the gap closes — our cascade with cross-check produces definitive verdicts where Bouncer returns inconclusive.
Switching from Bouncer in 5 minutes
- Sign up for MailCull Free. No credit card. 100 deep-scan checks plus 1,000 list rows for the first month.
- Test on your real list. Take 500-1,000 addresses with a heavy B2B mix. Run them through MailCull and compare to your Bouncer verdicts.
- If the verdicts hold up, upgrade to Pro. $19/month flat. Money-back in 30 days if your bounce rate exceeds 3%.
- We match remaining Bouncer credits for 30 days. Email us your last invoice.
FAQ
Is MailCull truly free or is there a catch?
100 deep-scan single-checks and 1,000 deep-scan list rows every month, recurring. Quick-scan unlimited. Read-only API access included. If you need more, Pro is $19/month flat.
Does MailCull have the same EU privacy posture as Bouncer?
We are not EU-headquartered, so on data sovereignty Bouncer wins. We are GDPR-compliant via Standard Contractual Clauses, auto-delete uploaded data after 30 days (Pro: 90 days), and offer a one-page DPA. For most non-procurement-gated buyers this is sufficient. For procurement-gated EU buyers, Bouncer is the right answer.
Does MailCull do SMTP mailbox verification?
Yes — full SMTP probing with STARTTLS opportunistic upgrade, FCrDNS-matched EHLO, IPv6 dual-stack support, and a per-MX rate limiter. Plus the M365 HTTP enumeration cascade. Documented at mailcull.io/methodology.
Why publish 91-93% when Bouncer claims 97%+?
Different test corpuses, different methodologies. We measure verdict-vs-actual-bounce-rate on a mixed corpus including catch-all and M365 hybrid edge cases. We claim what we measure.
Does the free tier API include the evidence chain?
Yes. The full 20-code evidence chain is in every API response, on every tier including Free.
The bottom line
If you respect Bouncer but want either a free recurring tier or the SMTP receipts they do not surface — MailCull is built for both reasons.
Start free with 100 deep-scan checks per month, no credit card. Or paste an email into the free single-email checker right now to see the evidence chain.
If you want a deeper comparison, the full MailCull vs Bouncer side-by-side covers pricing, accuracy data, and the feature parity table.