city mail

Mail sorted to the three-digit zip code level, destined for a non-unique three-digit zip code area. (A non-unique three-digit ZIP code is shared by more than one city.) A three-digit ZIP sort uses the first three digits of the ZIP code, which represent a group of contiguous cities. Mail sorted to the city mail level is eligible for a postage discount, which varies by class of mail and method of preparation, such as sacked mail. See also city sack; unique three-digit city.