A catch-all email domain, also called an accept-all domain, is configured to accept mail sent to any address at that domain, even mailboxes that do not exist. If you email random-gibberish@company.com and the company runs a catch-all, the message does not bounce; it lands in a central inbox that catches everything. Organisations use this so they never miss a message sent to a mistyped or former address.
Why catch-all domains cannot be verified normally
Email verification confirms a mailbox by opening an SMTP conversation with the receiving server and asking whether the address exists. On a catch-all domain the server answers yes to every address, real or not, because that is what it is configured to do. So the verifier cannot tell a live mailbox apart from a non-existent one. An honest verifier returns a separate status, usually risky or accept-all, rather than guessing deliverable.
Why catch-all rows still matter
Catch-all addresses are common, making up roughly 9 to 15 percent of an average list and often more on B2B lists, so you cannot simply discard them without losing reach. But they are unconfirmed: the person you are trying to reach may have left, leaving a mailbox that technically accepts mail but is never read. Sending to catch-all rows on your primary identity also carries bounce risk, because some of those addresses are genuinely dead despite the positive SMTP answer.
How to handle catch-all addresses
- Flag, do not guess. Keep catch-all rows in their own status so you decide consciously rather than treating them as confirmed.
- Use a separate identity. If you want to pursue them, send on a separate warmed sending identity so any bounces do not touch your main domain.
- Enrich before sending. A catch-all address paired with other confirming signals, such as a recent role or activity, is a safer bet than one with no other evidence.
In ReplyLabs, catch-all addresses are returned as a distinct risky status next to the deliverable and undeliverable verdicts, so you can filter and triage them rather than sending blind.