Whenever you start marketing to customer segments you should use different UTM or other tracking codes to be able to track each campaign separately.
Some systems like Repeat Customer Insights can work out their purchases without a tracking code but many systems cannot and could attribute those sales as new customer sales. Especially if it's been awhile since they've visited your store or have switched devices (i.e. cookies can get lost or expire).
Adding a UTM code is easy and is used automatically by Google Analytics to give proper attribution to your segmenting campaign. Other analytics systems might use other codes but I've seen quite a few support Google's UTM anyways.
Eric Davis
Segment your customers automatically with RFM
Segmenting your customers has always been touted as a powerful marketing tool but many stores avoid it because it can be time-consuming.
Repeat Customer Insights will automatically segment your entire customer base for you based on the valuable data Shopify has already collected for you. Ranging from 5 to 30 to over 125+ different segments using RFM and other models, you can pick how much power you want to harness.