Apply a coupon code via URL in WooCommerce
When you send a coupon code in an email then a recipient has to:
1. Select the code 2. Copy it to clipboard 3. Paste the code on the Cart page 4. Click on Apply coupon
You can make your customers life easier by sending a link that will automatically apply the coupon code.
Then, in your email template in Mailchimp you can construct the URL like this:
Mailchimp will show an error message that the URL is invalid. It's because * and | are not acceptable in a web address. You can safely ignore it and click Insert. Mailchimp will replace the merge tag with an actual coupon code before sending the email, and the final URL will be valid.