Mailchimp

Datafly Signal delivers behavioural events to your Mailchimp audience server-to-server using the Marketing API Add Event endpoint. Each event is attached to an existing contact (matched by email) and records a snake_case event name plus event properties. You can use these events for behavioural segmentation, event-property merge tags, and — on paid marketing plans — automation triggers.

Prerequisites

Before configuring Mailchimp in Signal, you need a Mailchimp Marketing API key, your data-center prefix, and the Audience (List) ID you want events attached to.

Configuration

Configure in Signal

1. Go to Integrations > Add Integration > Mailchimp.
2. Enter your api_key, dc, and list_id.
3. Select the consent categories that should gate delivery (typically marketing).
4. Choose the Default variant and click Save.

API Endpoint

POST https://{dc}.api.mailchimp.com/3.0/lists/{list_id}/members/{subscriber_hash}/events

• Authentication: HTTP Basic — the username is ignored and the API key is the password. (Mailchimp also accepts Authorization: Bearer {api_key}.)
• {subscriber_hash} is the MD5 hash of the lowercased contact email. Signal derives this from each event’s identified email, so the event lands on the correct contact.

Identity Signals

Mailchimp matches every event to a contact by email address. Signal needs an identified email on the event to compute the subscriber hash.

Call datafly.identify() when a user logs in, registers, or submits a form:

datafly.identify("user-123", {
  email: "jane.doe@example.com"
});

Signal lowercases and trims the email, then sends the event to that contact’s Mailchimp record. Events for visitors with no known email are dropped — there is no contact to attach them to.

Event Mapping

The Default preset maps Signal’s snake_case events to Mailchimp event names:

Mailchimp recommends a verb_noun naming convention with an underscore delimiter, which these names follow. Event context is recorded under the Mailchimp properties object. To customise, edit the integration’s Field Mappings in the Management UI.

Example: Order Completed

Datafly.js call:

datafly.identify("user-123", { email: "jane.doe@example.com" });
 
datafly.track("Order Completed", {
  order_id: "ORD-001",
  revenue: 129.99,
  currency: "USD",
  coupon: "WELCOME10"
});

Mailchimp Add Event request sent by Signal:

POST https://us6.api.mailchimp.com/3.0/lists/a1b2c3d4e5/members/{md5(jane.doe@example.com)}/events

{
  "name": "order_completed",
  "occurred_at": "2026-06-06T12:00:00+00:00",
  "properties": {
    "order_id": "ORD-001",
    "revenue": "129.99",
    "currency": "USD",
    "coupon": "WELCOME10"
  }
}

Testing

1. Add a known test contact to your audience (e.g. via the Mailchimp UI), then trigger an event for that email from your site.
2. In Mailchimp, open Audience > All contacts, click the contact, and check the Activity feed — the event appears with its name and properties.
3. Build an event-based segment (Audience > Segments) on the event name to confirm the event is queryable.
4. On a paid marketing plan, you can also wire the event to an automation as the trigger.

Troubleshooting