Catch-all domains and greylisted servers make up 30–50% of B2B lists. Most verifiers mark them unknown and stop. HeroBounce scores every address and retries every greylist — so you keep the contacts that matter.
100 free validations • No credit card required
Connects with your entire stack via REST API
Catch-all domains and greylisted servers account for a large portion of B2B email - and most validators return “unknown” without attempting to resolve them.
Catch-all domains account for 30-40% of all B2B email addresses. Standard validators return “unknown” and stop - leaving a significant portion of every list unactionable.
Large organizations routinely configure catch-all DNS as a security measure. “Unknown” does not mean invalid - it means your validation tool reached its limit.
Valid / Invalid / Unknown forces a choice between protecting sender reputation and discarding qualified pipeline. HeroBounce resolves the ambiguity.
Clean your email lists in 3 simple steps
Drag & drop your CSV file. We support lists of up to 10,000 emails per upload.
Our engine checks syntax, DNS, MX records, and SMTP - then actively resolves catch-all and greylisted emails instead of marking them unknown.
Get a clean list with confidence scores on every email - not just valid/invalid/unknown - so you can make informed decisions.
Resolves 50-70% of catch-alls instead of returning 'unknown'.
| Feature | HeroBounce | Competitors |
|---|---|---|
| Greylisted Email Handling | Auto-retry (~87% resolved) | Unknown |
| Catch-All Resolution | 50-70% Resolved | Unknown |
| Accuracy Guarantee | 95%+ | 95% |
| Pricing / 10k emails | $17 | $65+ |
| Domain Intelligence | ||
| Pattern Discovery |
Stop guessing and start knowing. Our enterprise-grade verification engine gives you the confidence to hit send.
We don't just say 'unknown' - we analyze patterns, domain behavior, and historical data to give you real answers.
Sub-second API responses with smart caching. Bulk jobs run live SMTP verification on every address — accurate results, not pattern-matched guesses.
Identify spam traps, complainers, and toxic addresses before they damage your sender score.
Greylisted servers temporarily reject unknown senders before accepting them. We automatically retry — resolving most greylisted emails within minutes at no extra cost.
Validated domain configurations are cached for 90+ days. Repeat domains resolve significantly faster and with higher confidence as our knowledge builds.
Clean REST API with SDKs for all major languages. Start integrating in minutes.
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