A small Node.js Fastify service to check if an email is already subscribed to your newsletter.

• Lookup if an email is already subscribed (/lookup)
• Returns structured result, built with TypeScript

Clone the repo and install dependencies:

git clone <repo-url>
cd lookup
npm install

Create a .env file, BREVO_KEY is needed.

Start the server in development mode:

npm run dev

You can test the lookup endpoint:

curl -X POST "http://localhost:5001/[email protected]"

or

node src/test.ts [email protected]

Example response if subscribed:

{
  "customer": { "emailStatus": "already_subscribed" },
  "action": {
    "customFields": { "isSubscribed": true },
    "privacy": { "optIn": true }
  }
}

If not subscribed:

{}

npm run build

This will compile TypeScript into dist/.

Run production server:

node dist/server.js

TBD

• POST /lookup?email=<email> – Returns subscription status for the given email.

• It is implemented only for LC

Looks like that elixir when using lookup can pass data other than just email - supporter_id, org_id, action_page_id, and custom_fields (needs to be confirmed). This allows implementing org-specific logic in the future without changing the core. For example, we could branch behavior based on org_id or apply custom rules per organization while still using the same endpoint for the basic email subscription check.