The setting is recommended to prevent duplicate customers in your Retail Express database. 
As of Version 5.2.4 March 2021 we no longer look at the Export flag in customers following customer Feedback.


We also have an option to check by email address only and ignore the First and Last Name

To edit these settings within REX, navigate to
Settings > POS Settings > Customer Settings

There are two checkboxes that need to be unchecked:

  • Allow Duplicate Customer Emails

Further down is 

  • Default Export to Web Service to Enabled for new customers

Make sure to save your changes to avoid needing to edit these settings again.