Log in to your Mailchimp account.

Click your account icon (your initials) in the upper-right corner.

Select Profile from the menu.

Click Extras, and then select API keys.

Scroll to the Your API keys section. Existing keys cannot be viewed or copied again after they are created.

Click Create A Key. Mailchimp generates the key.

Click Copy to Clipboard and save the API key in a safe place for later use.

Click Done. Your new key is listed in the Your API keys section.

Go to Subscriptions Management > Subscriptions and click Search Certified Integration Marketplace and Subscribe. ​

Click the Mailchimp Integration title. ​

On the Subscription Detail page, click the Subscribe button.

Enter the Name of the subscription and select a Version. The name can be any relevant, unique subscription name within the company where the subscription is created.

Select Create Default Mappings (recommended). If you want to create all mappings yourself, clear this checkbox. ​

Provide the API Url for your Mailchimp account, in the form https://<region>.api.mailchimp.com (for example, https://us13.api.mailchimp.com). Use the region prefix shown in your Mailchimp browser address.

Enter the API Key you generated in Mailchimp.

(Optional) Enter the Variant External Id Delimiter. This is the single character that separates the product identifier from the variant identifier when the integration builds a variant's external identifier. For example, using the pipe character (|) with product ID 12345 and variant ID 67890 produces the external ID 12345|67890.

(Optional) Enter the Special Character Replacement. This is a safe character (such as _ or -) that replaces reserved characters in product and variant identifiers before they are sent to Mailchimp. Reserved characters such as /, ?, or # can break the request. When the integration encounters one of these characters in an identifier, it substitutes your configured replacement character. If your identifiers can contain these characters and no replacement character is configured, those updates fail with an error.

(Optional) Set Use Store Id From Transaction to true or false. When set to true, the integration carries the store identifier from each incoming order through to the related customer, product, and variant records, keeping them associated with the correct Mailchimp store. When set to false or left blank, the order's store identifier is not propagated in this way.

(Optional) Enter the Customer Store Id Custom Field Name. This is the name of the customer custom field that the store identifier is written to and read from. It is used together with Use Store Id From Transaction to locate the store identifier on customer records.

Enter the API Throttle Limit. This controls the number of API requests the subscription can make within the throttle window, protecting system performance and ensuring fair usage.

Enter the API Throttle Seconds. This defines the time window over which the API Throttle Limit is measured. If the subscription exceeds the limit within this window, additional requests are held until the window resets.

Enter the number of Concurrent Connections. This specifies the maximum number of simultaneous API connections the subscription can process. If the limit is exceeded, new requests are queued or rejected until an active connection finishes.

Enter the number of Concurrent Batch Executions. This specifies the maximum number of simultaneous batch executions that can process for the subscription at one time. If the limit is exceeded, new requests are queued or rejected until an active execution finishes.

Click Apply to save the settings.

Initiate a sample data push from iPaaS.com to Mailchimp.

Confirm the record (for example, a customer or order) appears in Mailchimp.

Run an end-to-end business process.

Validate key behavior such as field mappings and record creation in Mailchimp.

Review integration activity under Dashboard / Integration Monitoring / Error Logs in iPaaS.com to confirm there are no errors.