CRMs

Check email domains, website contacts and domain authority in folk

Check the email domain of every person in your folk groups so a shared list of contacts is free of throwaway and role addresses before you write to it.

Why the data matters in folk

folk keeps people in groups that a team shares and mails from. A single throwaway or role address copied into a group travels to every teammate who works that list, so one bad import becomes bounced messages and muddy relationship history for several people at once.

What LookValid checks

LookValid checks for folk
Product	What it does here	Credits
Email Domain Check	Returns a good, risky or undeliverable signal from the domain mail records of each address. It does not test that a mailbox exists. Marks addresses on disposable domains and free providers, which helps you separate company contacts from personal ones inside a group.	1 credit per address checked
Website Contacts Scraper	Reads a public company page and returns the contact details it publishes, as a starting point for people who have no email yet.	10 credits per domain with contacts found
Domain Authority	Gives a 0 to 100 link-graph score for a company domain, an input for ranking which groups to work first. It is not Moz or Semrush authority.	10 credits per domain found in the rank data (an unranked domain is free)

Connect it in four steps

Create a LookValid account and an API key from your dashboard, which a person does once in the browser.
Set LOOKVALID_API_KEY in the shell session or the scheduler that runs the script, and keep a folk API key, made in the API section of your workspace settings, in a second variable that the folk calls send as a Bearer header.
Run the script once per email, pacing the loop because folk allows 600 requests a minute and 20 in any two seconds: a null result means nothing could be read, and a failure prints the error code and its fix and stops the loop.
Create text custom fields such as email_signal on the group first, then send the three values with PATCH /v1/people/{personId}, placed in customFieldValues under the id of that group and keyed by the exact field names.

A shell job that reads one email per line, taken from the people you list through the folk API, and prints one check result per line. The call is POST https://YOUR_API_HOST/v1/email-domain-check and costs 1 credit per address checked.

check_folk_email.sh

1#!/bin/sh
2# Usage: check_folk_email.sh <value>
3set -eu
4jq -n --arg value "$1" '{"email": $value}' \
5  | curl --fail-with-body -sS -X POST "https://YOUR_API_HOST/v1/email-domain-check" \
6      -H "Authorization: Bearer $LOOKVALID_API_KEY" \
7      -H "Content-Type: application/json" \
8      -d @- \
9  | jq 'if .error then ((.error.code + ": " + .error.fix + "\n") | halt_error(1)) elif .found then {"email_signal": .data.deliverability_signal, "free_provider": .data.free_provider, "disposable": .data.disposable} else null end'

Where each response field goes in folk
Response field	Goes into
data.deliverability_signal	email_signal
data.free_provider	free_provider
data.disposable	disposable

The recipe returns nothing when the lookup finds nothing, which costs no credits for this product, and stops with the error code and fix on a failed request.

Without code

An automation platform with a generic HTTP request step can run the same check with no dedicated app. Create a folk webhook for the person.created event that points at the platform. folk sends only the person id and a URL for fetching the record, so add one HTTP step that reads the person from that URL with your folk key, a second that posts the email to the LookValid email-domain-check endpoint, and a third that sends the signal back with a PATCH request.

REST and MCPOne shared credit balance

Questions

What does checking a group cost?

One email-domain-check lookup per address, at the credit rate on the pricing page. A group of fifty people is fifty lookups.

Will it tell me which addresses will bounce?

It tells you which domains cannot or should not receive mail. A good domain can still bounce for a mailbox that does not exist, which this check cannot see.

Where do the keys live?

The LookValid key sits in the LOOKVALID_API_KEY environment variable of the machine running the job. The folk key goes in its own variable. Neither belongs in a list of emails you save to disk.

Will the update wipe the person's other values?

The folk update call changes only the fields you send. List fields such as emails and phones are replaced as a whole when sent, so leave them out and send only customFieldValues.

Sources

folk Developer Portal, Update a person https://developer.folk.app/api-reference/people/update-a-person, read 2026-10-18
folk Developer Portal, Custom fields https://developer.folk.app/core-concepts/custom-fields, read 2026-10-18
folk Developer Portal, Create webhooks https://developer.folk.app/webhooks/create-webhooks, read 2026-10-18
folk Developer Portal, Events and payloads https://developer.folk.app/webhooks/events-and-payloads, read 2026-10-18
folk Developer Portal, Rate limits https://developer.folk.app/api-reference/rate-limits, read 2026-10-18
folk Developer Portal, Authentication https://developer.folk.app/api-reference/authentication, read 2026-10-18
LookValid API reference: Email Domain Check https://lookvalid.com/docs/api/email-domain-check, read 2026-10-18

LookValid is run by Meralume Labs. It is not connected to, endorsed by or a partner of any company or product named on this page, and every product name belongs to its owner.

LookValid bills every lookup in credits from one shared balance, so the same key works for each check above.

See Email Domain Check