I use multiple shipping carriers and DO ship to PO Box address as long as the customer selects the Postal Service as the shipping carrier.

Since Zen Cart defaults to the cheaper carrier they sometimes select the wrong carrier and it delays shipping of the order because we have to contact them for a regular street address or change it to postal service and charge them the difference in shipping.

I would like to add a check so if the shipping address is a PO Box then it will override the default logic and select USPS as the carrier as well as block them from continuing on if they try to select UPS or FedEx...anyone else having this issue?