Accept-all and Unknown, honestly explained

Some answers no validator can give you. Here is what accept-all really is — and why unknowns cost you nothing.

What accept-all means

An accept-all (catch-all) domain is configured to accept mail for every address — real or not. When a server says yes to anything, there is no protocol-level way to confirm whether one specific mailbox exists. That is not a limitation of one tool; it is how the domain chose to behave. Any service claiming to fully verify individual mailboxes on accept-all domains is guessing and labeling it certainty.

We tell you the truth instead: the verdict is accept-all, the domain infrastructure is real and receiving, and the individual mailbox is unverifiable from the outside.

What to do with accept-all addresses

• Treat them as a separate segment — never mixed into your cleanest sends.
• Prefer addresses with engagement history; a past open outweighs any validation.
• Introduce them gradually and let real bounce data prune the segment.

What unknown means — and the refund

An unknown verdict means we could not get a definitive answer in time — a server that never responded, a DNS timeout, an aggressive tarpit. Rather than dress a non-answer up as a result, we mark it unknown and automatically refund the credit when the job settles. You pay for answers, not attempts.