Catch-All Verification
How to verify emails on accept-all domains with True-Send™.
Catch-all (accept-all) domains present a unique verification challenge. This guide explains what they are, why they matter, and how True-Send™ technology provides definitive verification where standard SMTP checks fail.
What is a Catch-All Domain?
A catch-all domain is configured to accept emails sent to any address at that domain, regardless of whether the specific mailbox exists. This is common in:
- Corporate environments — Companies use catch-all to ensure no customer email is lost due to typos
- Small businesses — Often enabled by default in many hosting configurations
- Legacy systems — Older mail servers may have catch-all enabled without IT knowing
The Problem: When you ask a catch-all server "Does user@domain.com exist?", it always answers "Yes"—even for completely fake addresses like asdfgh123@domain.com.
Why Standard Verification Falls Short
Standard SMTP verification performs these checks in sequence:
Validates email format (user@domain.tld)
Confirms domain exists with valid mail servers
Connects to mail server and asks if mailbox exists
Server accepts everything → Email marked as "Risky"
At step 4, verification hits a wall. The server accepts all addresses, so we cannot distinguish between john.smith@company.com (real employee) and nobody.here@company.com (non-existent).
How True-Send™ Works
The only way to truly verify a catch-all email is to send a real email and monitor for bounces. True-Send™ does exactly this—safely and at scale.
True-Send™: Send email → Monitor → Bounced = Invalid, Delivered = Valid
Micro-Email Sent
We send a tiny, non-promotional email from our dedicated sending infrastructure. No links, no tracking pixels, just pure verification.
Bounce Monitoring
We monitor for hard bounces over 24-72 hours (you choose). Bounced = Invalid. Delivered = Valid.
Your Reputation Protected
Emails are sent from our IPs, not yours. Your sender reputation is never at risk during verification.
Definitive Results
99%+ accuracy. No more "Risky" ambiguity—you get clear Valid or Invalid status.
When to Use True-Send™
- • B2B email lists with corporate domains
- • High-value outreach campaigns
- • Legacy lists with many "Risky" results
- • When sender reputation is critical
- • Before launching major campaigns
- • Speed is more important than 100% accuracy
- • List is primarily consumer emails (Gmail, Yahoo)
- • You're comfortable with 15-25% bounce risk
- • Low-stakes transactional emails
Choosing a Monitoring Window
| Window | Best For | Trade-off |
|---|---|---|
| 24 Hours | Urgent campaigns, time-sensitive lists | May miss some delayed bounces (~95% accuracy) |
| 48 Hours ★ | Most use cases (recommended) | Best balance of speed and accuracy (~99%) |
| 72 Hours | Maximum accuracy, large enterprise lists | Catches all delayed bounces (~99.5%) |
Quick Start: Run a Catch-All Verification
Upload your list and run normal verification. Emails marked "Risky" are catch-all candidates.
Download the "Risky" segment from your results page.
Upload the risky list and select "Catch-All Verification". Choose your monitoring window.
After the monitoring window, download your verified list with definitive Valid/Invalid status.
Plan Availability
True-Send™ catch-all verification is included in Growth and Scale plans. Credits reset monthly.