1. Open your Settings

Log into your Shopify store and on the bottom left of the screen, select "Settings."

2. Select "Checkout"

Under Shopify Settings, select the "Checkout" option.

3. Scroll down to "Abandoned checkouts"

Scroll down to "Abandoned checkouts" and select when you'd like to send out the abandoned cart email.

4. Select "Customize email"

5. Customize your abandoned checkout email

You can use variables in these emails found here.