Save this search & be the first to know when new listings hit the market! Windsor Mill MD is recognized as the preferred city name for zip code 21244 mailing addresses by the postal system yet they also consider the city of Baltimore MD as an acceptable alternative.ave this search & be the first to know when new listings hit the market! Windsor Mill MD is recognized as the preferred city name for zip code 21244 mailing addresses by the postal system yet they also consider the city of Baltimore MD as an acceptable alternative.