Introduction
Do you want to add an opt-in checkbox on the PEP (Product Enquiry Pro) enquiry form which will add your customers to the MailChimp subscription list?
PEP 6.5.0 comes with this feature. Here is a screenshot of the PEP setting and subscription checkbox on the enquiry form:

Configuration
Follow the steps below to enable the subscription checkbox on your enquiry form which will add your customers to the MailChimp subscription list:
- Install the plugin Mailchimp for WooCommerce
- Activate and setup the plugin
- Enable subscription checkbox on PEP enquiry form
Install the Plugin Mailchimp for WooCommerce
Mailchimp for WooCommerce plugin is a free plugin developed by MailChimp. You can get it by clicking here. Install the plugin on your site and move to the next step.
Activate and Setup the Plugin
After activating the plugin Mailchimp for WooCommerce, you will be redirected to the following page:

Click on the CONNECT ACCOUNT button or CREATE ACCOUNT button and follow the three steps required to complete the setup. You will get a guide on each screen for the setup.
Once you have setup the plugin successfully, you should see the following screen:

Enable Subscription Checkbox on PEP Enquiry Form
Navigate to the PEP settings tab Form [Product Enquiry Pro > Settings > Form]. Now look for the section MailChimp options under the same Form tab.
If you have done the setup of the plugin MailChimp for WooCommerce successfully, you should be able to see the section MailChimp options as shown below:

Now, enable the setting Show Subscription Checkbox and let your customers enroll into your MailChimp subscription list.