What is a catch-all email address?
A catch-all (or accept-all) domain is set up to accept email for any address, whether the mailbox exists or not. Because the server says yes to everything, an email verifier can't confirm the individual mailbox, so it reports the address as catch-all rather than valid.
Capabilities
Everything Mailcleaner ships with.
Layered checks
Risk and confidence
Bulk list cleaning
Suppressions and re-checks
Domain audit
API and widget
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What is a catch-all email domain?
Normally a mail server rejects mail for a mailbox that doesn't exist. A catch-all server instead accepts everything sent to the domain, and either delivers it to a shared inbox or quietly discards it.
Companies set this up so mail with a misspelt name still arrives, or so nothing gets lost when staff leave. Some large consumer providers behave in a similar way for verification purposes, accepting every address when checked.
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Why can't verifiers confirm catch-all addresses?
An SMTP check relies on the server rejecting mailboxes it doesn't know. A catch-all server never rejects, so the check gets the same yes for jane@ as for a made-up address. Any verifier that calls those addresses valid is overstating what it knows.
Flaxxa Mailcleaner reports them as catch-all, with a catch-all score, so you can decide how to treat them.
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How does catch-all detection work?
After checking the real address, the verifier asks the same server about an address that can't exist, such as a long random string. If the server accepts that too, the domain is catch-all and the yes for the real address carries no weight.
Flaxxa Mailcleaner runs this test on Standard checks and above, and never caches a catch-all verdict, so a later check looks again.
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Should you send email to catch-all addresses?
Don't delete them all: many are real people at real companies. Don't treat them as valid either.
- Keep catch-all addresses that have opened or clicked your mail recently.
- Send to the rest in smaller batches, after your engaged contacts, and watch bounces.
- Suppress any that bounce, straight away.
- Through the API, pass an engagement hint (engaged or last_engaged_at) and Flaxxa Mailcleaner confirms a recently engaged catch-all address as valid without sending anything.
Catch-all email addresses: common questions
It may be. The domain accepts mail, but the specific mailbox can't be confirmed, so it is uncertain rather than valid or invalid.
Put it to work
Mailcleaner features for this
Catch-all detection
Find catch-all (accept-all) domains in your email list. Flaxxa Mailcleaner tests each server, scores catch-all domains and never passes them off as valid.
The checks
The checks behind each verdict: syntax, typo, disposable and role detection, MX lookup, an SMTP mailbox check, catch-all detection and deeper signals.
List cleaning
Clean an email list in one upload: counts per verdict, a clean CSV or XLSX export, and a suppression list so bad addresses don't creep back in.
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