Use Case
Clay users chain Findymail → ZeroBounce → MillionVerifier because no single tool is trusted enough. MailSentry’s 11 layers and extended depth mode replace the entire waterfall in one API call.
No credit card · No overage charges · Credits never expire
The problem
what teams pay chaining validators
tools in a typical Clay waterfall
providers that publish their accuracy
The waterfall exists because every provider returns a boolean — valid or invalid — and none of them agree. When Tool 1 says valid and Tool 2 says invalid, you need Tool 3 to break the tie. You’re not paying for accuracy. You’re paying for lack of confidence.
The solution
11 validation layers + extended depth mode replace the entire waterfall.
Syntax, MX, disposable, role-based, free provider, typo correction, SMTP, gibberish, spam trap, domain age, and abuse detection. Every layer runs in parallel. One request, one score.
Pass "depth": "extended" and we re-probe SMTP after a 3-second delay. Greylisting servers that reject the first probe accept the second. Catch-all detection gets a second confirmation. The exact scenario that breaks waterfall workflows — solved in one call.
A 0-100 quality score with verification_level (confirmed/inferred/estimated) and catch_all_confidence. You get probability, not a coin flip. One confident score replaces three conflicting booleans.
We publish our accuracy methodology and back it with a guarantee: if more than 3% of emails we mark valid bounce within 30 days, we credit your account. No other provider makes this commitment publicly.
In practice
Extended depth mode with a single API call.
{
"email": "sarah@stripe.com",
"depth": "extended"
}{
"email": "sarah@stripe.com",
"score": 95,
"verdict": "valid",
"verification_level": "confirmed",
"verification_depth": "extended",
"checks": {
"smtp": { "valid": true, "catch_all": false,
"mx_host": "aspmx.l.google.com",
"greylisted": false },
"free_provider": { "is_free": false, "is_business": true,
"mx_provider": "Google Workspace" },
"domain_age": { "age_days": 5942, "risk_flag": null },
"disposable": { "is_disposable": false },
"gibberish": { "is_gibberish": false, "score": 100 },
"spam_trap": { "is_potential_trap": false }
},
"response_time_ms": 4200
}Extended depth takes 4–8 seconds (vs. 1–5s standard) because of the SMTP re-probe delay. Use it for high-value leads where confidence matters more than speed.
Comparison
| MailSentry | 3-Tool Waterfall | |
|---|---|---|
| Validation layers | 11 in one call | 1 per tool (need 3 tools) |
| Greylisting handling | Extended depth re-probes automatically | Manual retry or accept the false negative |
| Catch-all confidence | 0-1 score based on local-part analysis | Binary valid/invalid — no nuance |
| Result format | 0-100 score + per-layer breakdown | Boolean or 3 conflicting booleans |
| Monthly cost at 50K | $29/mo (Pro plan) | $130-500+/mo (3 tools combined) |
| Accuracy guarantee | 3% bounce = account credit | None published |