Membership ranks are stored in customer metafields, allowing you to save segments and use them for marketing purposes.
See: How to Create a Customer Segment for Each Rank
To send an email, set the saved segment as the recipient and send it using your Email app. The following steps use Messaging, the official Shopify email app. Shopify email app.
https://apps.shopify.com/shopify-messaging
Go to Customers > Segments and select the segment name you configured

In the Segments list, click ⋯ next to the segment you want to use, select Use segment, then select Email.

Select a template and edit the content of the email to be sent. Note: Only customers who have agreed to receive marketing emails will be included as recipients.
Click Send test to preview the email content.

<aside> 💡 Note: In a development store, the following error may appear. Please test on a live store instead. "Error: The store is blocked and cannot send test emails. Please contact support.”
</aside>


