How to verify accept all emails?

Accept-all, also known as “catch-all,” is a domain-wide setting where every email address on that domain accepts mail during the SMTP handshake - whether or not a real mailbox exists behind it. That’s what makes catch-all domains impossible to verify with a standard check: the server says “yes, deliverable” to everything, valid or not.

The risk of catch-all emails

Increased bounce rate - Unpredictable bounces are the biggest risk to your sender reputation and the main reason to be extremely cautious with catch-all addresses. Since a standard verifier can’t tell a real mailbox from a dead one on a catch-all domain, most tools just label the whole batch “risky” and either flag it for manual review or make you guess. Send to enough of them blind and your bounce rate creeps up, which is exactly what damages domain reputation and inbox placement for every campaign after it.

So how do you actually verify them?

You can’t do it with a plain SMTP handshake - that’s the whole problem with catch-all. What you need is a verifier built specifically to determine deliverability within a catch-all domain, not just detect that it is one.

That’s the one thing BounceBan is built around. Instead of flagging every catch-all address as “risky” and stopping there, it uses its own verification logic to estimate which catch-all addresses are actually live - covering Google Workspace and Microsoft 365 domains, and mailboxes sitting behind major Secure Email Gateways like Mimecast, Proofpoint, and Barracuda. Single-email verification is free and unlimited, so you can spot-check a handful of catch-all addresses before deciding whether a list is worth sending to at all, and bulk verification is available if you need to clean a full list before a campaign.

We don’t run their infrastructure so we can’t independently verify their exact accuracy numbers - their own published claims cite 85-95% accuracy on catch-all/greylisted/SEG-protected addresses, and their customer reviews describe bounce rates dropping from the 4-8% range down to under 1-1.5% after switching. Worth checking yourself before you rely on it at scale, but it’s a real answer to a problem most verifiers just wave a flag at instead of solving.

Try BounceBan free and run a few of your own catch-all addresses through it before your next campaign.