Catch-all domain

A catch-all domain (also called accept-all) is configured so its mail server accepts mail sent to any address at the domain, whether or not a mailbox with that name exists. During the SMTP conversation, the server answers 250 to RCPT TO for [email protected] and for [email protected] alike.

What happens next varies. The message may land in a shared catch-all mailbox, be bounced later after the server checks its directory, or be silently discarded. Some organisations set this up deliberately so misspelled addresses still reach someone; in other cases a security gateway in front of the real mail server accepts everything and decides later.

Verifiers detect catch-all behaviour by testing an address that almost certainly doesn't exist, such as a long random string. If the server accepts it, the domain is treated as catch-all, and a positive answer for any other address at that domain proves nothing on its own.

Catch-all domains are common among businesses, so B2B lists often contain a meaningful share of them. Treating these addresses as safe can produce delayed bounces; discarding them all throws away real prospects. Most teams send to catch-all addresses more carefully: in smaller batches, after confirming the name and email format, and while watching the bounce rate.

Skrap.ai detects catch-all domains and returns those addresses as Risky: the domain accepts everything, so the mailbox can't be confirmed. Risky results cost 1 credit, like Valid ones. Check any address with the free email verifier, and read catch-all emails explained for how to decide what to send.