Email Finder API: Inputs, Confidence and Cost per Lookup

An email finder API takes a first name, a last name and a company domain, and returns the person’s probable work email address, ideally with a signal of how sure it is. It exists because most professionals follow a company format, and a provider that knows the format and the person can narrow the guess to one address.

What goes in and what comes out

The inputs are deliberately small. In the BusinessMCP version, documented on its People Data API page, the request is a POST to /api/hub/v1/people/email-finder and takes three required fields: domain (up to 253 characters), first_name and last_name (each up to 60 characters). The same function is available to AI agents as the MCP tool email_finder.

The output is a work email with a confidence indicator. The page does not state the scale of that indicator, nor does it reproduce the response schema, so build your integration against the developer documentation rather than assumptions. What the page does state is how stored addresses are labelled.

Status	Meaning, per the provider’s page	How to treat it
valid	Last-checked status of an address in the store	Reasonable to send, still not a guarantee
catch_all	The company’s mail server accepts any address	Cannot confirm this mailbox exists
unknown	The check was inconclusive	Send cautiously or skip
pattern	Built from the company’s email format, unverified	A guess; expect some bounces

If those labels are new, our explainer on catch-all email addresses covers why that middle status causes so much confusion.

Why verification is the real question

Finding an address and knowing it works are different problems. The standard way to test an address is to open an SMTP conversation with the receiving server, as described in RFC 5321, and see whether it accepts the recipient. Many servers refuse to answer honestly, and catch-all domains accept everything. So even a careful verifier ends up with “probably”.

BusinessMCP is explicit about its approach: its email verification never opens an SMTP session and never says an address is valid; its best verdict is domain_ok, per its trust documentation. That is a conservative design, and it is a reminder to read what “verified” means in each vendor’s own terms. A service that claims certainty about a mailbox should explain how it got it.

Key takeaway: the confidence indicator on a found email is a statement about the provider’s evidence, not a promise of delivery. Track your own bounce rate and treat it as the final measure.

Pricing and what you pay for

The finder is priced at $0.04 per call, charged only when a result is found. That detail changes the economics compared with credit systems that charge for the attempt. If you submit a list of 1,000 names and the service finds 600 addresses, you pay for 600 lookups, not 1,000, and the page says nothing about a minimum.

It also means the hit rate shapes your real cost per usable lead. A cheap call that finds few addresses is not cheap per outcome. The page states no hit-rate figure, so run a sample. The pricing article shows how to compute cost per usable contact across several billing models.

For comparison, BusinessMCP’s own comparison with other vendors cites Hunter, which it says charges one credit per found email and half a credit per verification. That detail comes from BusinessMCP’s company data API comparison, which says prices were checked in late September and early October 2026; check Hunter’s own page for current terms.

A sensible workflow

1. Discover the person. Use people search or your CRM to get a name and domain. If you only have a company, search comes first.
2. Normalise the inputs. Strip titles and nicknames from names, and use the company’s primary domain, not a marketing microsite.
3. Call the finder. Store the returned address, its status and the date you retrieved it.
4. Segment by status. Send to valid first, test small batches of catch_all and unknown, and keep pattern addresses for low-risk outreach only.
5. Feed back results. Log bounces so you can see which statuses actually perform.

The longer guide to finding a work email from a name and company covers the manual versions of these steps for when you have no budget for an API.

Rules that apply after you find the address

An address in hand is not permission to send. In the United States, the CAN-SPAM Act sets requirements for commercial email such as accurate headers, a clear opt-out mechanism and honouring opt-outs promptly, as the FTC’s compliance guide explains. In the EU, UK and Switzerland, consent and legitimate-interest rules apply to marketing to individuals, and the picture differs between business and consumer addresses and between countries. This is not legal advice; take it to counsel before launching a campaign.

There is also a provider-side limit. BusinessMCP never returns people located in the EU, EEA, UK or Switzerland, and excludes people placed in California, Texas, Vermont and Oregon. If your target market sits there, the finder will return fewer results by design. Opted-out people are removed within about a day, so refresh data rather than relying on an old export.

Reading the economics with a worked example

Suppose you want addresses for 500 named buyers. At $0.04 per found address, if the service finds 350 of them you spend $14.00, which is about four cents per address and about five cents if you count only the valid and catch_all ones you actually send to. Those numbers are an illustration of the arithmetic, not a forecast; the provider publishes no hit rate. The point is to measure three things on your own list: the share found, the share of found addresses that bounce, and the cost per delivered message. A finder that returns more addresses but bounces more can lose to a stricter one.

Also decide what you do with misses. Falling back to a guess built from a common pattern such as first.last at the domain may recover some contacts, but sending to guessed addresses damages sender reputation when many bounce. If you must guess, send in small batches and stop when the bounce rate climbs. BusinessMCP also sells an email-pattern lookup in its company data API at $0.01 per call when found, which returns the address format plus MX and catch-all information for a domain; that is useful for understanding a domain even when no individual address is found.

When to use it, and when not to

Use an email finder when you have a named target and need a reachable work address, for example after a call or a conference scan. Skip it when you only have a company: search first. Skip it when the purpose is consumer-style tracing of individuals, which falls outside what business-contact APIs are for, and the BusinessMCP page prohibits using people data for credit, employment, insurance or housing decisions.