SimpleVerifier Team · Reviewed
What is a catch-all email and should I send to it?
A catch-all (accept-all) domain is a mail server set up to accept mail for any address at the domain, real or not, so a verifier cannot confirm that a specific mailbox exists. Send to catch-all addresses selectively: test a batch of 100 to 300, measure the bounce rate, then send only as many as your limit allows.
Why they cannot be confirmed
During a mailbox check the server is asked whether it would accept mail for an address. A catch-all server says yes to everything, including addresses nobody owns. Any later bounce, if it happens, comes after the message is accepted. SimpleVerifier tests a made-up address at the domain first, so a catch-all domain is detected and its addresses come back as risky, not valid.
A practical rule
Score catch-all addresses by where they came from (a person's own signup beats a scraped guess), send a test batch from the best group, and compare the bounce rate with your platform's line. With 100 sends and no bounces you can be about 95% confident the real rate is under 3%; with 300 and none, under 1%.
Related questions
- Are catch-all addresses valid?
- Some belong to real people and some do not. The server accepts them all, so only sending reveals which, and that is why they are marked risky.
- How common are catch-all domains?
- It varies by list. B2B lists often contain many because small companies commonly run catch-all mail, so measure your own list with a catch-all check.
Sources
Figures marked as ours come from SimpleVerifier’s own dated tests on made-up addresses, published with their data on the research page. No customer data is used, and we publish no accuracy percentage because we have no independent measurement to back one.
Do it now
Test it on a real address first
Type any address. It gets the same check the paid plans run: syntax, the domain’s mail servers and, where the provider allows it, a live mailbox check. Nothing is sent to the address.
Five checks a minute, no account needed. Nothing is sent to the address — we ask its mail server whether the mailbox exists, then disconnect.
Have a list? Sign in with Google and the first 100 addresses are checked free, with results to download. No card.
By continuing you agree to our Terms and Privacy Policy.