Depth tiers
Depth controls how hard we work to reach a verdict. Deeper checks prove more but cost more and take longer. You pick the tier; we tell you which tier actually ran.
| Depth | What it does | What it proves | Cost |
|---|---|---|---|
syntax | Parses and normalises the address. No network calls. | The address is well-formed and not obviously junk. Nothing about deliverability. | Always free, for everyone, including anonymous callers. |
mx_only | Everything in syntax, plus a DNS lookup of the domain’s mail servers (MX). | The domain can receive mail. Not that the specific mailbox exists. | Metered per new record (see billing). |
full | Everything in mx_only, plus a live SMTP conversation with the mail server to test the specific mailbox. | The strongest signal we offer: the server accepted (or rejected) this recipient. Still bounded by catch-all behaviour. | Metered per new record (see billing). |
Requested vs applied depth
You request a depth, but the depth we apply can differ. If your plan does not include live SMTP probing, a full request gracefully degrades to mx_only; if a dependency is down, a check can fall back further. Each result reports the depth that actually ran, so you are never billed for a deeper check than you received.
Syntax is free precisely so you can clean obvious garbage out of a list at no cost before spending credits on the addresses that are worth probing.
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