BounceProtect
Clean your email lists before you send
What is a Catch-All Domain?
Domains that accept email to any address — even ones that don't exist.
A catch-all domain is configured to accept email sent to any address at that domain — even addresses that don't exist. If example.com is catch-all, then xyz123@example.com receives mail even if that mailbox doesn't exist.
Why this matters for senders
Because catch-all domains accept everything, we can't verify whether a specific email address has a functioning mailbox. Two risks:
- Silent bounces — the domain accepts the email at the server level, but it may be silently discarded internally with no bounce notification.
- Reputation risk — high volumes of email to unmonitored catch-all addresses can trigger spam detection at ISPs.
How we detect catch-all
We send a probe to a randomly generated, definitely-invalid address at the domain (e.g., noverify-xyz@domain.com). If the server accepts it, we flag the domain as catch-all.
Catch-all confidence levels
| Confidence | What it means |
|---|---|
| High | Multiple probes accepted — strong catch-all signal |
| Moderate | Probes accepted but server behaviour was inconsistent |
Special case — security gateways
Domains using Mimecast, Proofpoint, or Symantec always appear as catch-all because these gateways accept all mail at the network edge and filter internally. We apply provider-specific rules and note this in the results.
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