Catch-All Domains

A catch-all (or accept-all) domain is configured to accept emails sent to any address at that domain, whether the mailbox exists or not. This makes it impossible to confirm via SMTP alone whether a specific email address is real.

What Is a Catch-All Domain?

Most email servers reject messages sent to non-existent mailboxes with a "550 User not found" response. Catch-all domains skip this check and accept everything. This means sending to anything@catchall-domain.com will not bounce, even if no one reads it.

Approximately 20-30% of B2B domains are configured as catch-all, making this a common challenge for email verification.

How GTMData Handles Catch-All

GTMData uses two techniques to provide useful results on catch-all domains:

Convention Confidence

When using the Email Finder on a catch-all domain, GTMData analyzes the domain's naming convention by testing known employees. If a strong pattern is detected (e.g. 80%+ of verified employees use first.last), the finder returns the most likely email with a high confidence score.

SMTP Timing Analysis

Some catch-all servers respond differently for real vs. non-existent mailboxes. GTMData analyzes SMTP response timing and behavior patterns to distinguish real addresses from catch-all noise. When this signal is strong enough, the result is upgraded to valid_catchall.

Status Meanings for Catch-All

Status	Meaning	Confidence	Charged?
`catchall`	Domain is catch-all. Best guess based on convention patterns.	Medium (0.5-0.85)	No
`valid_catchall`	Domain is catch-all, but SMTP timing + convention signals strongly suggest this email is real.	High (0.85-0.99)	Yes (finder only)

Tips for Handling Catch-All Results

Tip: Use the confidence score to decide how to handle catch-all results. A score above 0.85 is generally safe to email.

For outbound campaigns: Include valid_catchall results in your sends. For plain catchall results, consider including those with confidence above 0.8 but monitor bounce rates.

For CRM hygiene: Mark catchall results as unverified in your CRM. Only treat valid and valid_catchall as confirmed.

For deliverability:If you send to catch-all addresses, use a dedicated sending domain or subdomain to protect your primary domain's reputation.

Warning: Never send to catch-all addresses in bulk without monitoring. While the emails will not bounce, sending to non-existent mailboxes can hurt your sender reputation over time.