Free Tool

Free Catch-All Email Detector

Check if a Domain Accepts Emails to Any Address

Identify catch-all (accept-all) domains that accept mail to any email address, even non-existent ones. Improve lead quality and targeting.

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What Is a Catch-All Domain?

A catch-all (also called "accept-all") domain is a mail server configured to accept emails sent to ANY address on that domain, whether the specific mailbox exists or not. Instead of bouncing invalid addresses, the mail server accepts them and typically routes them to a catch-all mailbox or forwards them to an administrator.

For example, if example.com is set up as a catch-all, emails sent to non-existent addresses like [email protected], [email protected], or [email protected] will be accepted instead of bounced. This is different from normal mail servers which only accept emails for legitimate, configured mailboxes.

While catch-all domains serve legitimate purposes (catching emails to misspelled addresses, handling generic inquiries), they create challenges for email marketers and lead generators who cannot verify if a specific email address actually belongs to a real person or mailbox.

Why Catch-All Detection Matters

Catch-all domains create significant challenges for email marketing and lead quality.

Can't Confirm Real Mailboxes

Catch-all domains accept emails to ANY address, so you can't verify if a specific person actually uses that email address.

Higher Bounce Risk

Emails may be delivered initially but bounced later if the catch-all eventually filters them out or forwards to non-existent addresses.

Waste Marketing Budget

Emails to catch-all domains consume credits but may never reach a real person, wasting marketing spend.

Inflate List Sizes

Your subscriber counts appear larger because you're including unverified catch-all addresses.

How Catch-All Detection Works

Our detection uses SMTP testing to identify domains configured as catch-all.

1

SMTP Handshake

We connect to the domain's mail server and initiate an SMTP connection.

2

Test with Random Address

We test the domain by attempting to send an email to a randomly generated address that definitely doesn't exist (e.g., [email protected]).

3

Compare Responses

If the mail server accepts the non-existent address without rejecting it, we've identified a catch-all. Normal servers reject invalid addresses; catch-all servers accept them.

What to Do With Catch-All Results

Handle catch-all domains strategically to improve your email program.

Segment Separately

Create separate segments for catch-all and non-catch-all addresses to apply different marketing strategies.

Lower Sending Priority

Send to catch-all addresses at lower priority or with different sending frequency to manage reputation.

Monitor Bounce Rates

Track bounce rates for catch-all addresses separately to understand delivery performance.

Re-engagement Campaigns

Consider re-engagement campaigns for catch-all addresses before removing them from your list.

Need More Power?

Upgrade to MailRook's full email verification suite for bulk catch-all detection, API access, and complete email validation.

Bulk catch-all detection
API for integration
Full email verification

Frequently Asked Questions

Not necessarily. Catch-all has legitimate uses (preventing lost emails, catching typos). However, for B2B prospecting and lead generation, catch-all addresses are problematic because you can't verify if the address belongs to a real person.
Our detection is highly accurate, using direct SMTP testing to identify catch-all behavior. We test with genuinely non-existent random addresses to confirm whether the server accepts everything or validates properly.
It varies significantly by industry and domain type. Large enterprises rarely use catch-all (maybe 5-10%), while small businesses are more likely (15-25%). The percentage depends heavily on your specific target market.
Yes! Our paid plans include API access that lets you integrate catch-all detection directly into your signup flows, email platforms, or custom applications.
It depends on your strategy. For B2B prospecting, removing catch-all improves list quality. For B2C or large organizations, you might keep them but segment and monitor separately. A/B testing different approaches is recommended.
Yes! This catch-all detector is completely free. No signup required, no credit card needed. Try it now to check if any of your email domains are configured as catch-all.

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