For Reward follow up sequence, click on the Reward from the left side menus

 

Then click on Settings and then Email Notifications as shown in the image below

In this section, click on the Reminder Notification to find the mail content 

Note: This Email reminder will be sent to the customers automatically  when the reward is about to expire. Email will be sent once in a day for 1 week before it expires

 

SMTP should be integrated for the mailing process

 

For the first time, Save the mail content in this section and then you can find a toggle to enable this mail . Make sure that the toggle is in active status