// FREE TOOL
Email Verifier
No signup. No limits. Same continuous check we run on every managed mailbox.
Why bounce rate matters
Hard bounces are the fastest way to burn a domain. Keep cold email bounce rate under 3%; above 5% and providers throttle or block.
Hard vs soft bounces
Hard: permanent (invalid address). Soft: temporary (full inbox, outage). Suppress hard bounces immediately; retry soft sparingly.
Catch-all explained
Some domains accept any address. Verification confirms the domain accepts, but not that the specific person exists. Treat as risky.
Verification as hygiene
Verify every list within 24 hours of sending. Older verifications go stale.
Common questions
Single-address checks: free, unlimited. Bulk verification: free with an account.
CLAYINBOX runs this check continuously on every domain it manages — automatically.