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Glossary

What does accept-all mean?

Quick answer

Accept-all is the verification result for an address whose mail server said yes to every recipient, including made-up ones. It means the server will not reveal whether the mailbox exists, not that the mailbox is real. Treat accept-all addresses as their own risk tier: score them, send to the strongest ones first and watch the bounces before mailing the rest.

Definition

Accept-all: A verification result for an address on a domain whose mail server accepts every recipient at the RCPT TO stage. The address may or may not have a real mailbox, so the result is a risk signal rather than proof of deliverability.

What causes an accept-all result

The most common cause is a domain set to catch-all, where every local part is delivered to some mailbox. The second is an email security gateway in front of the real server that accepts every recipient during the SMTP conversation and checks mailboxes afterwards.

A smaller group of servers simply skip recipient checks at RCPT TO and decide after the message arrives. For a verifier, all three look identical: a 250 reply to an address that should not exist.

How accept-all differs from deliverable and unknown

Deliverable means the server accepted the address and rejected a random one, so the yes was meaningful. Unknown means the server gave no clear answer at all, because of a timeout, a block or greylisting.

Accept-all sits between them. The server answered clearly, but the answer was yes to everything, so it carries no information about this specific mailbox.

How to send to accept-all addresses safely

Split them out of your main send. Mail the best-scoring addresses first in a smaller batch, ideally ones with a known name and a local part that matches the company pattern.

Suppress hard bounces immediately and stop mailing any accept-all segment whose bounce rate climbs. Recent engagement, such as a reply or a click, outweighs any verification signal.

How RocketVerifier handles it

In the dashboard and the current API version (RocketVerifier-Version: 2026-11-01), accept-all addresses are returned as risky with sub_status catch_all and a catch_all_verdict of send_safe, send_with_caution or avoid. Older API keys on the legacy version see the same addresses as unknown. If the random-address probe is blocked or times out after the real address was accepted, the result is unknown, because an accept-all domain has not been ruled out, and unknown results are never charged.

Go further

Sources

  1. RFC 5321: Simple Mail Transfer Protocol

FAQ

Accept-all: common questions

Are accept-all addresses covered by the bounce guarantee?

No. The bounce guarantee covers addresses a job marked deliverable. Addresses returned as risky, catch-all or unknown are excluded, which is why the catch_all_verdict exists: it tells you which ones are worth the risk.

Can I test an accept-all address by sending it an email?

A test send only tells you something if it bounces. Many accept-all servers drop or reroute mail without any bounce, so silence proves nothing, and a batch of test sends that do bounce counts against your sender reputation.

Why do accept-all results show up more in B2B lists?

Company domains often run catch-all routing or sit behind security gateways that accept everything at the edge. Large consumer providers such as Gmail reject unknown mailboxes outright, so their addresses rarely come back accept-all.

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