DynamicZip currently supports only the U.S.A. and Canada.
You may have customers who do business in other countries that have ZIPs/Postal Codes similar to the U.S.A. (For example; Italy, Mexico, Australia, Malaysia, etc.). In this situation, you need a way to restrict DynamicZip functionality to only affect the supported countries. Otherwise, Tax Schedule Selection might assign U.S. Tax Schedule to the foreign addresses, and ZipAddressing could change the foreign addresses into U.S. addresses.
DynamicZip has options to allow restricting Tax Schedule Selection and/or ZipAddressing to only the United States and Canada. These Restrict By Country options can be enabled via the DynamicZip Setup window and must be used in unison with the Country Default options. With these options selected, DynamicZip will check the value of an address's Country Code field to verify that it matches either the U.S. or Canadian setting for Country Default on the DynamicZip Setup window prior to modifying the record.
For help with setting up Country Default please see How do I set the default country value for my U.S. customers?
NOTE: Prior to DynamicZip build 72, the Country Code field was not used for this functionality. Instead, this functionality was based on the Country field (Which is now basically a Country Code Description field). We switched to using Country Codes after Microsoft added the Country Code functionality in Microsoft Dynamics GP 10.