Email verification

Choose a verifier

Settings → Email verification lets you use ColdPegion built-in or your own ZeroBounce/BillionVerify API key. Automatic prefers ZeroBounce if both keys are saved, then BillionVerify, otherwise built-in. Provider errors remain visible and do not silently switch providers. Third-party checks use your provider credits.

What built-in checks establish

The engine checks syntax (including IDN domains), MX/null-MX/implicit mail routing, a versioned disposable-domain list, role accounts and likely domain typos. It does not automatically correct addresses or assume Gmail/Outlook domains are catch-all.

Direct SMTP checks are disabled on the current GCP deployment because external port 25 is restricted. Mailbox existence therefore stays Unknown after DNS checks. Where direct probes are enabled on suitable infrastructure, only recipient-level rejection establishes invalidity and a random control-recipient test distinguishes catch-all acceptance. No test guarantees future inbox delivery or detects all spam traps.

Imports and sending

The CSV import dialog supports background verification using your selected verifier. Contacts wait while the check is pending. Known invalid, disposable, spam-trap or provider do-not-mail results are excluded from campaign sending. Unknown means unconfirmed; it does not receive a verified badge. An unknown address can still be eligible after the check completes; review that risk before sending.

Use Verify beside a contact or verify_email over MCP for a fresh check. Saved provider keys are encrypted and are never returned in plaintext.