The Mailchimp integration copies your customers' email addresses into one of your Mailchimp audiences, so you can send campaigns from Mailchimp using your own templates.
Settings → Mailchimp Integration. Admin only, and the Mailchimp module has to be enabled for your store — otherwise the tab reads "The Mailchimp module is not enabled on your account."
Get the two values from Mailchimp
The screen tells you exactly where each lives:
- API Key* — "In Mailchimp: Account & Billing > Extras > API keys > Create A Key"
- Audience ID* — "In Mailchimp: Audience > All Contacts > Settings > Audience name and defaults > Audience ID"
Connect
- Paste both values in.
- Select Save Changes.
- Select Sync Now.
A successful sync reports how many went across — "N customer email addresses syncronised".
If it fails you get Unable to connect to Mailchimp - check your API Key and List ID. That message covers three cases: a wrong key, a wrong Audience ID, and an audience your key has no access to. Re-copy both from Mailchimp rather than guessing which.
It also runs by itself
You do not have to press Sync Now to keep the list fed. Once the credentials are saved, a nightly job syncs every store that has them, so customers who order tomorrow are picked up automatically. Use Sync Now when you want the list current immediately, or to check the connection after changing a key.
Which customers are sent
Not all of them. A customer is sent only if all of these are true:
- Their account is active, or they are a guest.
- They have not opted out of marketing email.
- They have not turned off marketing for your store specifically.
- They have placed at least one order at your store, dated 2019 or later.
- They have not already been sent across on a previous sync.
Customers using an Apple private relay address (@privaterelay.appleid.com) are always skipped — mail to those addresses would not reach a real inbox you own.
So a low number after a sync is usually correct, not a failure. The commonest reasons are that most of your customers were already exported by an earlier run, or that they have never ordered from you.
The important limitation — unsubscribes do not flow back out
Each customer is exported once. After that, the sync never revisits them.
That means a customer who unsubscribes from your offers after being exported stays in your Mailchimp audience. mypreorder's unsubscribe page, our opt-out records and the STOP handling on SMS have no reach inside Mailchimp.
Once a list is in Mailchimp, honouring unsubscribes on it is yours to do, in Mailchimp. Mailchimp records its own unsubscribes when someone uses the link in your campaign, so keep sending through Mailchimp's own unsubscribe footer and never re-import a cleaned list over the top of it.
Mailchimp or Customer Announcements?
Both send marketing email, and they are not the same thing:
- Customer Announcements sends from within the portal, respects every opt-out we hold, adds the legally required sender details and unsubscribe link for you, and can combine push, SMS and email in one send. See Send an announcement to your customers.
- Mailchimp gives you Mailchimp's designer, automations and reporting, at the cost of owning the compliance yourself.
Section 14 of the merchant terms applies either way — you are the sender.