You can validate local delivery postal codes in the checkout, to prevent customers from seeing the wrong rate when changing their address at checkout.
By default, Validate against selected location is selected.
Enable postal code validation
In Settings, click Local delivery.
In the Checkout section, find Checkout postal code validation.
Choose your validation method:
No validation
Show delivery rates without checking the postal code entered at checkout. The rate selected in the cart widget will always be displayed, regardless of any postal code changes made during checkout.
Validate against selected location (recommended)
Only show a delivery rate if the postal code entered at checkout matches a postal code configured for the location selected in the cart widget. If the postal code doesn't match, no rate will be shown.
Validate across all locations
Check the postal code entered at checkout against the postal codes configured for all locations and show the matching delivery rate, even if it belongs to a different location than the one selected in the cart widget. If the postal code doesn't match any location, no delivery rate will be shown.
Note: No other settings are checked, only the postal code availability. The ZapietID and order attributes will show the original selected location.
Click Save.
Your validation method will now be saved, and customer postal codes will be validated at checkout accordingly.
Limitations
Only merchants using Zapiet - Pickup + Delivery rates can use this feature.
Validate across all locations checks only the postal code. It does not validate product availability, delivery dates or times [Shopify limitation].
When using Validate across all locations, if a delivery rate from a different location is applied, the attributes and ZapietId will not be updated, and there will be no indication that the rate came from a different location. To make this clearer, you can rename location-specific rates to make it clearer when a different rate was used.
When using Validate against selected location, if the customer changes their address then no rate will show, and no error message will explain that they need to use their original address to show a rate. You can edit the error message in your Shopify theme text editor to clarify customers need to change their address in the widget to proceed.
This setting is incompatible with delivery validation by city name. If you use city name validation, select No Validation to prevent checkout issues.
This setting will be hidden if you use No validation, Customer within maximum radius, Customer within maximum driving distance or Customer within a custom-drawn zone