What a reverse email lookup tells you
Most inbound is anonymous by default. A trial signup, a demo request, a reply from an address you have never seen: each arrives as a bare string with no name attached, and everything you do next depends on knowing who sent it. A reverse email lookup resolves that string into the person: their name, current role, and the company they work for, plus firmographics like industry, headcount, and location on the company side.
That single resolution is what separates a lead you can act on from a row you ignore. Route by company size before a rep ever opens the record. Score by seniority instead of by domain guesswork. Skip the "What does your company do?" discovery question because the answer arrived with the signup. Teams also run it defensively: an address whose claimed identity doesn’t match its resolved identity is a useful fraud signal at account creation.
The lookup runs live against the identity graph at request time; it is not a scrape of a static contact dump, so a person who changed jobs last quarter resolves to where they work now, not where an old CSV last saw them.
Business addresses only, by design
Paste [email protected] and the lookup runs. Paste [email protected] and it is declined before any work happens. That boundary is deliberate: a personal inbox belongs to a consumer identity, not a professional one, and resolving it would be both unreliable and the wrong kind of data to traffic in. Role accounts (info@, sales@, support@) are declined for the same reason: they belong to a team, not a person.
Disposable and relay addresses are turned away too. If you need to know whether an address is throwaway or whether the mailbox can actually receive mail, that is a different question, email verification, and it is a separate endpoint on the same API key.
In the API, an unsupported address is rejected with a clear error and costs nothing. You never pay to be told an address is out of scope.
Reading the result: confidence and partial matches
Every response carries a confidence grade (high, medium, or low) and it is worth respecting. A high-confidence match means the person and address lined up cleanly. A low grade means the graph found a plausible identity but could not corroborate it as strongly; treat it as a lead, not a fact, before you put it in front of a customer.
Partial results are real results. Sometimes the company behind the domain resolves clearly while the specific mailbox does not. You still learn which organization the address belongs to, its size, and its industry, which is often enough to route or score the lead. The free tool shows this honestly instead of padding a weak match into a fake person.
Billing in the API follows the same honesty: a lookup that resolves a person or a company bills at full price, one that finds nothing bills a small discovery fee, and an address that is out of scope costs nothing at all. Repeat lookups of the same address are served from cache, free.