First off you will need to set the app to use either exact postal code matching or partial postal code matching.
- Within the app click Settings
- Scroll down to the Delivery section and locate the Validation block
- Select Exact postal code match or Partial postal code match
- Click Save
How to specify the valid postal codes
Now you must tell the app which postal codes are eligible for delivery. You do this by modifying your Locations delivery settings.
- Within the app click Locations
- Click on one of your locations' names to reveal the edit page
- Locate the field called Eligible postal codes
- Enter a comma separated list of your valid postal codes into this field and click Save
Task complete! You customers will now be required to enter one of your eligible zipcodes before proceeding to the checkout process.