$ man waterfall

Waterfall

A sequence of fallback providers tried in order until one succeeds. The traditional approach to email finding — stack 4-6 providers and hope one hits.

I used to run 6-provider waterfalls — Apollo → Hunter → Clearbit → RocketReach → Prospeo → Dropcontact. it felt thorough. but when I layered in MX-based routing (Google → Instantly, non-Google → HeyReach), I realized the waterfall logic made no sense. I was burning 8-12 credits per contact chasing marginal coverage gains, and validation still bounced anyway. the routing layer downstream made most of that effort pointless. so I stopped. now I use one provider, validate with MX records, and route. simpler. cheaper. same deliverability.

I don't use waterfalls anymore. I go single-provider — Prospeo or LeadMagic — and check MX records instead of stacking fallback providers. if the single provider finds an email, I validate the domain's MX record (Google vs non-Google) and route: Google → Instantly, non-Google → HeyReach, no email → HeyReach for LinkedIn. the old waterfall burned credits trying to squeeze out emails that bounced anyway. single-provider + MX routing gets me the same result at a fraction of the cost. waterfalls are a concept worth understanding, but my philosophy is: don't use them.