Glossary
What is a catch-all email domain?
Catch-all domains are one of the main reasons email verification can't always give a yes-or-no answer.
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Definition
When a mail server is set to catch-all, it says yes to every recipient at the connection stage. Mail to a non-existent address may be silently dropped or routed to a shared inbox later.
Why catch-all domains create uncertainty
Verification works by asking the receiving server whether a mailbox exists. A catch-all server says yes to everything, so that answer carries no information.
Why they may return Unknown
Rather than guess, MailGuard marks these addresses Unknown. That keeps your Passed results trustworthy and means you aren't charged for an inconclusive check.
What to do next
- Keep catch-all addresses that came from real sign-ups or known customers
- Send to them in smaller batches and watch bounces
- Remove ones that came from unknown or purchased sources
Frequently asked questions
Are catch-all emails bad?
Not necessarily. Many legitimate companies use catch-all domains. They're simply impossible to confirm in advance.
Do catch-all checks use credits?
Addresses marked Unknown, including most catch-all results, use no credits.
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