I'm getting - "We're sorry, we cannot ship to this address."
If you are getting "We're sorry, we cannot ship to this address." on the checkout page even though everything appears to be correct, it could be due to several things. The most common reason is that the carriers are not configured inside of your EasyPost account. Be sure to confirm the carriers are active and selected at EasyPost. For example, if you have enabled UPS and FedEx in the Cart66 account, but your EasyPost account only has USPS enabled, then the rates coming back are going to get emptied out because none of them are going to match what they have configured in your Cart66 account, which will cause this message to show.
Sometimes not all delivery methods are available in all zip codes or with all box configurations. The reason being that if the carrier can not guarantee that delivery, it won't even show as a method.
Another example would be if you are offering "Media Mail" as an option and the delivery address is a PO Box. Unfortunately, the carrier simply does not support this method and you will get the "We're sorry, we cannot ship to this address." error.
If none of those steps correct the issue, make sure your carrier account is in a live mode and in good standing. Sometimes just not agreeing to something like a billing agreement will make the methods not show.
Sometimes when copying/pasting your API credentials a space will errantly be inserted into the field. Be sure you have the correct API credentials entered by going through that process a second time for good measure.