Articles on: Sync data

Sync STOQ customer data to Mailchimp for email marketing

STOQ can automatically sync customer data to Mailchimp whenever a visitor signs up for a back-in-stock or preorder alert on your store. Each synced customer is added to the Mailchimp audience you select, with a tag and their marketing consent status


Before You Begin


Make sure you have the following before you enable the Mailchimp integration:


  • A paid STOQ plan (the Mailchimp sync is not available on the free plan)
  • A Mailchimp account with permission to create API keys
  • STOQ installed and active on your Shopify store
  • An existing Mailchimp audience for STOQ to sync into. Create it in Mailchimp before you start.


Tip: STOQ uses the Mailchimp API to sync customer data. You will need a Mailchimp API key, which you can generate from your Mailchimp account settings.


How to Get Your Mailchimp API Key


Before you can connect STOQ to Mailchimp, you need to generate a Private API key in your Mailchimp account.


  1. Log in to your Mailchimp account.
  2. Click your profile icon in the top-right corner.
  3. Select Account & Billing.
  4. Navigate to Extras > API keys.
  5. Click Create New Key.
  6. Copy the generated API key and keep it somewhere safe. You will need it in the next section.


Note: Each Mailchimp API key includes a data center suffix (for example, -us21). Make sure you copy the full key including this suffix.


How to Connect Mailchimp and Enable Customer Sync


Follow these steps to connect your Mailchimp account and start syncing customers.


Step 1: Open the Integrations Page


  1. Open the STOQ app in your Shopify admin.
  2. Click Back in stock alerts in the left-hand menu.
  3. Navigate to the Settings section, then scroll to Integrations.
  4. Click Set up on the Mailchimp card.


Step 2: Enable the Sync Toggle


  1. Turn on the Sync visitors with Mailchimp toggle.
  2. Click Save in the top bar to confirm.


Step 3: Enter Your Mailchimp API Key


  1. After enabling the toggle, a Mailchimp API key field appears.
  2. Paste the API key you copied from your Mailchimp account.
  3. Click Save.


Once saved, STOQ validates the key and connects to your Mailchimp account. A green checkmark and "Your Private API key is configured" message confirm the connection.

Tip: If you need to update your API key later, click the Change link next to the confirmation message to reveal the key field again.


Step 4: Select Your Mailchimp Audience


  1. Under Audience, click Fetch audiences. STOQ loads the audiences in your Mailchimp account.
  2. Choose the one you want in the Select audience dropdown. Each option shows the audience name and its contact count.
  3. Click Save.


Once saved, the card reads "STOQ syncs profiles to the [audience name] audience/list on your Mailchimp account". Use the Change link next to it to switch audiences later.


Note: select the audience yourself. If you leave it unset, STOQ falls back to the first audience in your Mailchimp account, and if you have none it tries to create one named "Stoq!", which fails on accounts that restrict creating audiences.


Step 5: Set Your Profile Tag


  1. In the Settings section beneath the toggle, locate the Profile tags field.
  2. Enter a tag value (for example, restock-rocket or back-in-stock-signup).
  3. Click Save.


STOQ adds this tag to every customer it syncs to Mailchimp. The default value is restock-rocket.

Note: The profile tag is shared across all your enabled marketing integrations (Shopify, Klaviyo, Omnisend, Mailchimp). Changing it here updates the tag for every platform.


What STOQ Syncs to Mailchimp


STOQ sends detailed customer information to the audience you selected so you can segment and target your campaigns.


Customer Details


When a customer signs up for an alert, STOQ adds them to your selected audience with:


  • Email address (required — customers without an email are not synced)
  • First name (FNAME merge field)
  • Last name (LNAME merge field)
  • Phone number (PHONE merge field, if provided)
  • Tag (your profile tag value, default: restock-rocket)



STOQ sets the subscription status based on the customer's marketing preference:


  • Accepts marketing: Added as subscribed — they will receive your Mailchimp campaigns.
  • Does not accept marketing: Added as unsubscribed — their profile is stored but they will not receive campaigns.


Tip: STOQ sends back-in-stock notification alerts to your customers separately. The Mailchimp sync is for adding profiles to your Mailchimp list so you can use them in your own email marketing campaigns.


Choosing Your Audience


STOQ syncs profiles into the audience you select during setup. Create the audience in Mailchimp first, then pick it under Audience in the Mailchimp card.


If no audience is selected, STOQ falls back to the first audience in your Mailchimp account, and creates one named "Stoq!" if the account has none. Some Mailchimp accounts block audience creation at the account level, and that request then fails silently, so always select an audience explicitly.


Known Limitations


  • The Mailchimp integration requires a paid STOQ plan. Free-plan stores cannot enable it.
  • Email is required. Customers who sign up with only a phone number or push notifications are not synced to Mailchimp.
  • STOQ syncs customers one at a time as they sign up. There is no bulk retroactive sync for customers who signed up before you enabled the integration.
  • The profile tag field is shared across all marketing integrations. You cannot set a different tag for Mailchimp and Shopify independently.
  • If the Mailchimp API key becomes invalid or permissions are revoked, STOQ automatically disables the integration and clears both the API key and the selected audience. You will need to re-enter a valid key and select your audience again to resume syncing.
  • STOQ creates new list members each time. If a customer with the same email already exists on the list, Mailchimp may return an error for that sync attempt.


Troubleshooting


Symptom

Likely Cause

Fix

Customers are not syncing to Mailchimp

The sync toggle is not enabled

Go to Back in stock alerts > Settings > Integrations > Mailchimp and turn on Sync visitors with Mailchimp

Customers are not syncing to Mailchimp

No API key is configured

Enter your Mailchimp API key in the Mailchimp API key field and click Save

Integration was automatically disabled

The API key is invalid or permissions were revoked

Generate a new API key in Mailchimp, re-enable the toggle, and enter the new key

A customer signed up but is not in Mailchimp

The customer signed up without an email

Mailchimp requires an email address. Phone-only and push-only signups are not synced

Customer appears in Mailchimp as "unsubscribed"

The customer did not opt in to marketing

This is expected. STOQ sets unsubscribed status for customers who do not accept marketing

API key field does not appear

The sync toggle is off or the store is on the free plan

Turn on the toggle first. If you are on the free plan, upgrade under Plans in the left-hand menu

Profile tag is not applied to synced customers

The profile tag field was empty when the customer was synced

Enter a tag value and click Save. The tag only applies to future signups

Customers are not syncing to Mailchimp

No audience is selected

Under Audience, click Fetch audiences, choose your audience, and click Save

Fetch audiences returns nothing or shows a warning

The key is invalid, or the audience belongs to a different Mailchimp account than the key

The warning text comes from Mailchimp. Check the key is current and includes its data center suffix, then click Fetch audiences again


FAQs


Q: Where do I find my Mailchimp API key?
A: Log in to Mailchimp, click your profile icon, go to Account & Billing > Extras > API keys, and click Create New Key. Copy the full key including the data center suffix.


Q: Does STOQ create a Mailchimp audience automatically?
A: No. You choose an existing audience during setup: under Audience, click Fetch audiences and select one. If you skip that step, STOQ falls back to the first audience in your account, and only creates one named "Stoq!" if you have none at all. That creation request fails on accounts with restrictions on creating audiences, so select your audience during setup.


Q. Can I sync customers who signed up before I enabled the integration?
A. No. STOQ only syncs customers going forward from the moment you enable the integration. Previously signed-up customers are not retroactively synced to Mailchimp.


Q: Will disabling the sync toggle remove customers from Mailchimp?
A: No. Turning off the toggle only stops new customers from being synced. Customers already in your Mailchimp list remain untouched.


Q: Why was my Mailchimp integration automatically disabled?
A: STOQ disables the integration if it detects that the API key is invalid or your Mailchimp account permissions have changed. Generate a new API key in Mailchimp, re-enable the toggle in STOQ, enter the new key, and select your audience again


Q: Can I sync phone-only customers to Mailchimp?
A: No. Mailchimp requires an email address for each contact. Customers who sign up with only a phone number or push notifications are not synced

Updated on: 22/07/2026

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