Email marketing

Check email domains, domain age and domain authority in Mailchimp

Check the domain behind each Mailchimp subscriber address and write the result into merge fields, so segments can set aside throwaway, role and domains that cannot receive mail.

Why the data matters in Mailchimp

A Mailchimp audience grows from forms, imports and checkout sign-ups, and every typo domain or disposable address in it drags down open rates and sender standing for the whole list. Because merge fields live on each member, a bad address keeps getting campaigns until someone notices it, so flagging it once at the moment it enters the audience keeps later sends clean.

What LookValid checks

LookValid checks for Mailchimp
Product	What it does here	Credits
Email Domain Check	Reads the address domain for mail routing records, mail authentication policy, disposable domains, free mailbox providers and role mailboxes such as info@. It never contacts the mail server, so it cannot confirm that one mailbox exists.	1 credit per address checked
Domain Age	Returns when a subscriber company domain was registered, which helps you separate long-standing business domains from ones created last week.	2 credits per registered domain (unregistered domains are free)
Domain Authority	Scores a business domain from open web-graph data so you can rank B2B subscribers by how established their company site is. An unranked domain is not proof of low standing.	10 credits per domain found in the rank data (an unranked domain is free)

Connect it in four steps

Create a LookValid account and generate an API key from the dashboard.
Store the key as the LOOKVALID_API_KEY environment variable of the function that talks to Mailchimp, next to your Mailchimp API key, never in the audience form or a merge field.
Send the subscriber address to the email domain check; if the answer says found is false, leave the member untouched, and if the API returns an error, log its code and retry later instead of blocking the signup.
Add LV_SIGNAL, LV_FREE and LV_ROLE as merge fields on the audience, then send the returned values in merge_fields on the PUT to the member URL, which Mailchimp keys by the MD5 hash of the lowercased address.

A serverless function or small web handler that receives a new subscriber, checks the address, then upserts the member with the result. The call is POST https://YOUR_API_HOST/v1/email-domain-check and costs 1 credit per address checked.

validateMailchimpEmail.mjs

1const API_URL = "https://YOUR_API_HOST/v1/email-domain-check";
2
3export async function validateMailchimpEmail(value) {
4  const response = await fetch(API_URL, {
5    method: "POST",
6    headers: {
7      Authorization: `Bearer ${process.env.LOOKVALID_API_KEY}`,
8      "Content-Type": "application/json",
9    },
10    body: JSON.stringify({
11      "email": value,
12    }),
13  });
14  const result = await response.json();
15  if (!response.ok) throw new Error(`${result.error.code}: ${result.error.fix}`);
16  if (!result.found) return null;
17  return {
18      "LV_SIGNAL": result.data?.deliverability_signal ?? null,
19      "LV_FREE": result.data?.free_provider ?? null,
20      "LV_ROLE": result.data?.role_account ?? null,
21  };
22}

Where each response field goes in Mailchimp
Response field	Goes into
data.deliverability_signal	LV_SIGNAL
data.free_provider	LV_FREE
data.role_account	LV_ROLE

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

If you would rather not host a function, build the same thing in any automation platform with a generic HTTP request step: trigger on a new Mailchimp subscriber, post the address to the LookValid endpoint with your key in the Authorization header, and add an update-member action that fills the three merge fields from the response. No dedicated LookValid app is involved; it is one POST and one mapping.

REST and MCPOne shared credit balance

Questions

What does a Mailchimp check cost in credits?

Each check spends credits from your LookValid balance. The current amount for the email domain check is listed on the pricing page.

Does it tell me a subscriber mailbox exists?

No. It inspects the domain only, so it can flag a domain with no mail routing, a disposable domain or a role mailbox, but a made-up name at a working domain still passes.

Where does the key go?

In the environment of the code that calls Mailchimp. Mailchimp accepts a bearer token for its own API, and your LookValid key sits beside it as a separate variable.

Sources

Mailchimp Marketing API: add or update list member https://mailchimp.com/developer/marketing/api/lists/members/upsert-member.md, 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