Scenario: Client needs to make zip code as mandatory in the sales order so that the customer without the zip code will not be able to save the transaction.
Solution:
As the address maintains a separate record, by standard we could only make the zip code mandatory in the address record. This would be applicable to the newly entered addresses only not for the existing one without zip code. We could make the zip codes a mandatory address record following the steps mentioned below.
Customization> Forms> Address Forms
Select the currently used address form.
Check the mandatory checkbox for the Zip.
Click Save