This is due to the fact that any map or mapping software is always a reflection of past reality. New houses, buildings and entire streets are added all the time, and ZIP code boundaries are subject to frequent change too. The USPS is usually more up to date than mapping products - MapPoint is only updated once a year and the USPS updates its records continually.



MapPoint tries to handle this issue by matching a street address it cannot find at the ZIP code (or county, or state) level, and presenting addresses that it cannot uniquely match in a "disambiguation" dialog so you can select what you believe is the right location.