Build an email validation waterfall

Steps

1. Select validators. Primary + fallback providers based on accuracy and cost.
2. Build waterfall. Syntax → MX → catch-all → spam trap, cheapest first.
3. Validate existing data. Run full CRM contact list through waterfall.
4. Gate outbound. Only validated emails enter sequences.
5. Bounce feedback. Webhook invalidates on bounce, auto-pauses campaigns.

Success criteria

Bounce rate below 2%. Zero unvalidated emails in active sequences.