Mailchimp Webhook Setup Guide

In the connection’s configuration, set Webhook Audience ID to the ID of the Mailchimp audience you want events from — or several as comma-separated IDs (e.g. a6b5da1054 or a6b5da1054,f7c8eb2165). A webhook is registered on each audience.

• Find audience IDs in Mailchimp under Audience → Settings → Audience name and defaults (the Audience ID field), or by calling the connector’s list_audiences action.
• Enter the IDs without spaces around the commas.

In the StackOne dashboard, open the Mailchimp connector profile and enable the webhook events you want delivered downstream. See the Available Webhook Events section below for the full list.

On account connection (or when event subscriptions change), StackOne registers a webhook on each configured audience on your behalf using the connected account’s credentials. Mailchimp verifies the endpoint when each webhook is created; StackOne answers the verification automatically.

Trigger a matching change in Mailchimp (for example, subscribe a test contact to the audience) and confirm the event reaches your downstream consumer.

• Mailchimp sends events as form-encoded HTTP POSTs; StackOne responds with 200 OK automatically.
• If the endpoint is unavailable or takes more than 10 seconds to respond, Mailchimp retries at increasing intervals over 75 minutes, and may disable webhooks that keep failing.

To receive events from more audiences, append their IDs to the Webhook Audience ID field (comma-separated). Avoid editing the field while webhooks are registered — the stored registration is paired with the audience list at creation time, so unsubscribe first, update the IDs, then re-subscribe. Webhooks orphaned by an out-of-sync edit can be removed in Mailchimp under Audience → Audience settings → Manage webhooks.

Changing your event selection re-registers the StackOne-managed webhooks. Disconnecting the account deletes them from every configured audience, stopping deliveries.

Events related to contacts on the audience.

• Email Subscribed (subscribe) — Fired when a contact subscribes to the audience
• Email Unsubscribed (unsubscribe) — Fired when a contact unsubscribes or is removed
• Profile Updated (profile) — Fired when a subscriber’s profile is updated
• Email Address Changed (upemail) — Fired when a subscriber changes their email address
• Email Cleaned (cleaned) — Fired when an address is cleaned from the audience (hard bounce or abuse complaint)

Events related to campaign sending.

• Campaign Sent (campaign) — Fired when a campaign to the audience finishes sending or is cancelled

Mailchimp delivers each event as an HTTP POST with an application/x-www-form-urlencoded body — a type field, a fired_at timestamp, and the event details under data.