Catch-All Detector

Identify accept-all mail servers that hide whether mailboxes exist. Assess bounce risk before you send and protect your sender reputation.

Catch-All Detector

See Through Hidden Domains

Standard SMTP verification cannot tell real from fake addresses on catch-all domains. Our multi-probe detection identifies these servers so you can make informed sending decisions.

Multi-probe SMTP analysis99% detection accuracyBounce risk scoring
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BillionVerify catch-all email address verifier result screen

What Is a Catch-All Domain?

Catch-all domains accept every incoming email β€” even to addresses that don't exist.

Accepts Everything

The mail server accepts any address at the domain, making it impossible to confirm whether a specific mailbox is real.

Hides Invalid Mailboxes

Standard SMTP checks always return 'valid' β€” only actual delivery reveals the bounce later.

Higher Bounce Risk

Lists with undetected catch-all addresses carry a 30–50% higher bounce rate risk over time.

Hidden Spam Traps

Spam traps are often hosted on catch-all domains, making them nearly impossible to detect without specialized probing.

How Catch-All Detection Works

Multi-step SMTP probing identifies accept-all servers with 99% accuracy.

Domain Analysis

MX records and mail server configuration are resolved and analyzed for catch-all indicators.

Pattern Testing

Multiple probes with known-invalid random addresses test how the server responds to nonexistent mailboxes.

Response Verification

Server response patterns are analyzed to distinguish true catch-all from normal acceptance behavior.

Risk Scoring

Each domain gets a risk confidence score based on probe results and sending risk classification.

99%

Detection Accuracy

Multi-probe SMTP analysis

30–50%

Higher Bounce Risk

Undetected catch-all domains

<3s

Detection Time

Per domain analysis

100

Free Daily Checks

No credit card required

Frequently Asked Questions

1. What is a catch-all email address?

A catch-all domain accepts emails sent to any address, even nonexistent ones. You cannot tell which mailboxes are real, so sending to them carries a higher bounce risk over time.

2. How does catch-all detection work?

We send SMTP probes to the domain's mail server and test how it responds to known-invalid addresses. If the server accepts everything, we flag it as catch-all. This method achieves 99% accuracy and never sends actual emails to recipients.

3. Should I send to catch-all emails?

It depends on your risk tolerance. Catch-all addresses carry 30–50% higher bounce risk. We recommend segmenting them into a separate list and monitoring performance closely before scaling sends.

4. How accurate is catch-all detection?

Our catch-all detection achieves 99% accuracy using multiple SMTP verification methods. We distinguish true catch-all servers from temporary configurations to give you reliable results.

5. Can I bulk check catch-all domains?

Yes. Upload a CSV to check thousands of addresses at once. You can also use the real-time API for on-the-fly detection. Both methods return the same structured JSON result.

6. Is there a free option?

Yes. You get 100 free checks per day, no credit card required. The API also has a free tier so you can test the integration before committing.

Catch-All Detector

Detect Risky Domains Now

Identify catch-all servers, assess bounce risk, and improve deliverability before you hit send.

100 free checks daily Β· 99% detection accuracy Β· No credit card required

99.9%
Accuracy
Real-time
API Speed
$0.00014
Per Email
100/day
Free Forever