Catch-All Domains: How Common, How Risky
What share of B2B domains accept all mail, why 'unknown' isn't good enough, and how to treat catch-alls.
Key findings
- ◆Around a quarter of B2B domains are catch-all, so 'unknown' is a huge bucket.
- ◆A risk score (not a binary unknown) recovers real contacts safely.
- ◆Catch-alls should be segmented by confidence, never blasted cold.
What a catch-all domain is
A catch-all (accept-all) domain accepts mail for every address — valid or not — so an SMTP check can't confirm the specific mailbox exists. Most verifiers throw up their hands and return 'unknown', leaving you to guess.
Catch-alls are common on B2B domains, where IT teams configure servers to never reject mail. That makes a flat 'unknown' a large, unhelpful bucket.
Why a score beats a shrug
Treating every catch-all as un-sendable throws away real contacts; treating them all as valid hurts deliverability. The better approach scores the risk so you can send confidently to the safe end and hold back the rest.
- Send to high-confidence catch-alls in your engaged segments.
- Hold low-confidence catch-alls out of reputation-sensitive sends.
- Never send a cold blast to an all-catch-all segment.
Methodology: Illustrative analysis modelled on catch-all prevalence across business domains. Figures are illustrative and will be updated with live anonymized data. Free to cite with attribution to BounceBlock.
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