This page describes how to use Census with Mailchimp.

🏃‍♀️⠀Getting Started

In this guide, we will show you how to connect Mailchimp to Census and create your first sync.


1. Connect Census to Mailchimp

In the Connections page in Census, click the Add Service button under the Service Connections section, and select Mailchimp.
You will be redirected to a page to log in to Mailchimp to authorize your account to Census. Once you enter your credentials and click the Log In button, you'll see a page like the image below, confirming you want to authorize Census.
Once you've authorized Census, you'll be redirected back to the Connections page in Census and you should see your Mailchimp connection there.
If you want to see your connections in Mailchimp in the future, simply navigate to the Profile page, and scroll down to the Connections and notifications section.

💡⠀Mailchimp Field Quirks

Please note that the mandatory status field only accepts the following values in lower case: "subscribed", "unsubscribed", "cleaned", or "pending".
With Mailchimp, the API endpoint needs a Status field value, so if you find yourself seeing this error:
Oh no!
But you don't want to overwrite existing Statuses in Mailchimp, you just need to provide a mapping to the field labelled, "Status For New Subscriber".
Then your test sync, or completed syncs will be good to go, like this one:
If you do want to update the Status field, you can include that instead. However, we highly recommend understanding your organization's implications of potentially re-subscribing a member that has previously unsubscribed.
For more details, take a look at Mailchimp's API documentation.

🗄⠀Supported Objects

Object Name
List/Audience Members
Email Address, Prehashed Email Address (update-only)

Prehashed Email Identifiers

To prehash your emails, first lowercase the email address and then apply an MD5 hash, both which can be done directly in SQL. For example, here's the SQL you'd use in Snowflake (syntax for other data warehouses vary slightly)
SELECT MD5(LOWER('[email protected]'))

Status and Unsubscribing List Members

The Mailchimp status field supports one of four values: subscribed, unsubscribed, cleaned, or pending. To unsubscribe a member from a particular list, simply set the status field to unsubscribed.


Mailchimp tags field can be set by providing an array of string values as structured data. Read more about syncing Structured Data using Census.

🔄⠀Supported Sync Behaviors

Learn more about what all of our sync behaviors on our Core Concept page.
Update or Create
Update Only

🚑⠀Need help connecting to Mailchimp?

​Contact us via [email protected] or start a conversation with us via the in-app chat.