Catch-all domains

Catch-all domains accept mail for any address, so a mailbox check cannot confirm one. How Kawaa reports them, and what to do with them.

What is a catch-all domain?

A catch-all (or accept-all) domain is configured to accept emails sent to any address at that domain, even if the specific mailbox doesn't exist.

The challenge

When a domain is catch-all, mailbox-level checks cannot definitively confirm whether a specific address exists. The server will accept emails for any address, making it difficult to distinguish between valid and invalid addresses.

How Kawaa handles catch-all domains

• After the mailbox is accepted, we send a second probe to a made-up address at the same domain. If that is accepted too, the result has the status catch_all, with sub_status catch_all and verification.catch_all set to true
• Some mail providers accept every recipient probe whatever the domain is set to. Those results also get the status catch_all, with sub_status provider_accept_all
• If the second probe could not be completed, the domain was never shown to accept everything, so the result is risky rather than catch_all
• The quality_score of a catch-all result is never above 60
• When AI analysis is on, ai.catch_all_confidence (0-100) estimates how likely this particular mailbox is to be real
• A catch-all result is never served from cache: checking the address again runs a fresh check

Recommendations

For catch-all emails:

• Consider the source - leads from reputable sources are more likely valid
• Start with smaller test sends to gauge bounce rates
• Remove emails that bounce on first send
• Monitor your sender reputation closely