I was recently set the task of integrating a Mailchimp mailing list to a WordPress website by way of a multi-step Gravity Form. The regular form fields were easy to link, but the interest groups needed a bit more research. Alongside regular list fields, you can add an interest group, so that subscribers can indicate what they’re interested in. By using these groups, you can run a single list, but target newsletters to specific groups of subscribers, according to their interests.
To create an interest group in Mailchimp, switch to Manage Contacts » Groups, add a group, then add group categories. Simple.
Now switch to the WordPress installation and add a Gravity Form with the same fields as you have in your Mailchimp mailing list. You’ll need to use the Mailchimp add-on (WordPress plugin) to connect the form to Mailchimp. Once the plugin is active, switch to the form’s Settings » Mailchimp panel. There, you can indicate which Gravity Form field relates to which Mailchimp field. That’s all relatively easy.
To set up interest groups, add a checkbox list to your Gravity Form. You’ll have to manually add the checkbox options to the field, as the Mailchimp add-on doesn’t automatically create these for you. (Remember to update the Gravity Form if you add or change the Mailchimp group categories.)
Once the Gravity Form checkboxes are created, switch to the Mailchimp feed settings in Gravity Forms. There, activate the checkbox for each interest group category. (These come from Mailchimp.) When the field here is active, choose Assign to group = if, then match your Gravity Forms field value to the Mailchimp interest group. This will ensure that activated checkboxes in your Gravity Form are passed over to Mailchimp when the form is submitted.