What is a catch-all domain?
Catch-all domains accept mail for every address — which makes individual mailboxes impossible to verify. What that means for your list, and how to handle it honestly.
The short version
A catch-all (or accept-all) domain is configured to accept mail for any address at that domain — real or not. anything@ reaches somebody's inbox, or a black hole.
Companies set this up so a misspelled employee name still arrives somewhere. The side effect: no outside system can tell whether a specific mailbox actually exists, because the server says yes to everything.
Why validators say “risky” instead of “valid”
An honest validator probes a catch-all domain, notices that a deliberately nonsense address is accepted too, and concludes that its yes means nothing. The address is deliverable at the domain level — but the individual mailbox is unknowable.
Tools that report catch-all addresses as “valid” are telling you what you want to hear. The mail might land, or it might rot in an unmonitored bucket that never bounces and never engages.
What to do with catch-all addresses on your list
Send to them — but watch them. A catch-all address that never opens anything across several campaigns behaves like a dead letterbox and quietly drags your engagement metrics down.
Segment catch-all addresses so you can see their performance apart from confirmed mailboxes, and retire the persistently silent ones the same way you would retire hard bounces.
Check your addresses now
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