Catch-all address
A mailbox that receives mail sent to any address at a domain that matches no real user, so the domain's server accepts every recipient instead of rejecting unknown ones.
What it means
With catch-all routing, a domain's mail server accepts mail for any local part and delivers whatever matches no account to one designated mailbox or group. Google Workspace offers it as a routing setting, so that mail sent to incorrect or non-existent addresses at the domain is not lost.
The side effect is that such a domain never answers user unknown: every RCPT TO is accepted. Address verification cannot tell a real mailbox from a non-existent one there, so verification tools report these domains as catch-all (or accept-all) instead of valid. The catch-all mailbox also collects whatever spam is sent to random addresses at the domain.
Related terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- Google Workspace Admin Help: Get misaddressed email in a catch-all mailboxknowledge.workspace.google.com
- RFC 5321, section 4.1.1.3: RECIPIENT (RCPT)rfc-editor.org
All 432 terms in the glossaryThe wiki: blocklists and bounce codes