What is a catch-all email address (accept-all domain)?

A catch-all (or accept-all) email domain is a mail server configured to initially accept incoming SMTP RCPT TO commands for any address at that domain—even non-existent or misspelled mailboxes—to prevent missing legitimate emails or to block spammers from harvesting valid employee directory names.

Why do catch-all emails still bounce after accepting SMTP RCPT TO?

Enterprise gateways like Mimecast, Proofpoint, Barracuda, and Microsoft 365 often accept the initial SMTP handshake (250 OK) to inspect the message body for spam first, and then generate an asynchronous Non-Delivery Report (NDR hard bounce) later if the internal mailbox does not exist.

How do I set up or check a Google Workspace catch-all email?

In Google Workspace Admin Console, navigate to Apps -> Google Workspace -> Gmail -> Default Routing, add a routing rule for 'All recipients', and under 'Also deliver to' or 'Change envelope recipient' route unrecognized addresses to a designated catch-all inbox. Use KaijuVerifier above to verify whether any Google Workspace domain has catch-all routing enabled.

Does KaijuVerifier charge credits for Unknown or Catch-All timeouts?

KaijuVerifier never charges credits for Unknown or Greylisted timeouts ($0 billing guarantee). For Catch-All domains, our 7-Layer Smart SMTP engine performs a randomized control probe, caches the domain status for 24 hours, and assigns a composite 0–100 deliverability score (Grade B/C) so you know whether a lead is safe for cold outreach.

RANDOMIZED CONTROL PROBE · GOOGLE WORKSPACE & M365 CATCH-ALL DETECTOR

Real-Time Catch-All Email Verifier & Domain Probe

Over 28% of B2B corporate domains are configured as Catch-All (Accept-All) servers that say 250 OK to every address during basic checks—only to hard-bounce later. Test any email or domain below with our randomized SMTP control probe, or drop your CSV/Excel list to isolate risky catch-alls in seconds.

Live Catch-All SMTP Control Probe

Enter any B2B email address (or domain like cloudflare.com) to test both the target mailbox and a randomized non-existent control address:

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What Is a Catch-All Email Address?

A catch-all email domain (also called an accept-all mail server) is configured to accept every incoming email sent to @company.com during the initial SMTP handshake—even if the specific username (like j.smith999@company.com) does not exist.

IT administrators enable catch-all routing for two reasons: so typos in sales inquiries still land in a general inbox, or as an anti-harvesting shield by security gateways (Mimecast, Proofpoint, Barracuda) that silently drop or bounce invalid messages after SMTP disconnect.

Google Workspace & Microsoft 365 Catch-Alls

In Google Workspace (Apps → Gmail → Default Routing) and Microsoft 365 Exchange Online (Mail Flow → Rules → Dynamic Distribution), admins frequently configure catch-all rules for startups and mid-market companies.

KaijuVerifier tests every domain with a cryptographically random control address (kv-probe-{rand}@domain.com) before testing your lead, caching the domain's catch-all posture for 24 hours and calculating a composite 0–100 Deliverability Score.

Catch-All Email Verification FAQ

Should I send cold emails to Catch-All (Accept-All) addresses?

Never blast unsegmented catch-all addresses from your primary sending domain. Instead, export your Valid (Grade A) leads for your main sequence, and throttle Catch-All (Grade B, Score 70–84) leads at no more than 15% of daily volume on secondary warmed domains.

How do I configure a Google Workspace catch-all email?

Open Google Admin Console → Apps → Google Workspace → Gmail → Default routing. Click Configure, select All recipients, under Envelope recipient choose Replace recipient with your catch-all mailbox, and under Options select Perform this action only on non-recognized addresses.

How much does bulk catch-all email cleaning cost?

You can clean up to 5,000 emails for a $19 one-time credit pack (credits never expire) or 10,000 emails/month for $19/mo on Starter. Unknown and Greylisted timeouts are always $0.