Complex sentence: Understand that, Campbellsport is primarily the main Zip Code or City/Village people in neighboring communities address their mail to through the United States Postal Service, and that most county residents that use the 53010 Zip Code don't actually reside within the village.
Split into simpler sentences: Understand that, Campbellsport is primarily the main Zip Code or City/Village people in neighboring communities address their mail to through the United States Postal Service. In fact, most residents in this portion of the county, that use the 53010 zip code, don't actually reside within the village.