Target a specific customer segment with a message. Go to 'Messages' in Loopy Loyalty. 

Select 'A segment of my customers'.

Then choose a segmentation: stamps earned, rewards earned, or rewards redeemed.

Then, let's specify the segment criteria. For example, 'less than'.

And finally input the amount. For example, 2 stamps:

Loopy Loyalty will calculate the number of customers for the segment that you chose so you'll know how many people you will be able to reach.