Catch-all domain

A catch-all (or accept-all) mail server says yes to every recipient, even to an address that does not exist, such as 'xyz123@company.com'. Some companies set this up on purpose so they do not lose mail sent to a misspelled address.

This makes verification hard. A verifier asks the server if the mailbox exists, and a catch-all server answers yes to everything. The result is usually shown as 'risky' or 'unknown'. The email may reach a person, it may be sorted later, or it may bounce after a delay.

Do not drop catch-all contacts by default, because many real businesses use this setup. Treat them as higher risk. Send to them in small batches, watch the bounce rate for that group alone, and keep them away from your first sends on a new mailbox. Where you can, find a second, verified contact at the same company. A direct address that you know is real is better than a guess.