Glossary
Catch-all domain
A catch-all domain is one whose mail server accepts messages for any address at that domain, whether or not a mailbox exists.
Why it matters when you send from your own Gmail
This defeats address checking. When a checker asks the server whether jane@example.com exists, the server says yes to everything, so a yes proves nothing. A message to a made-up address may be accepted, then bounce later, or be silently dropped. Many small businesses are catch-all without knowing it. For a sender the sensible stance is caution: treat addresses at catch-all domains as unverified, prefer a real named person found on the company's own site, and watch for late bounces.
Example
A checker asks about a clearly invented address at a domain, and the server accepts it. Every address at that domain is now unverified, however plausible it looks.
What to do
When a checker reports a domain as catch-all, send fewer emails there at first and watch for late bounces. An address you saw on the company's own website carries more weight than a guessed one.
Related terms
All terms are on the glossary.