In message , at 00:30:21 on Tue, 3 Aug
2010, David A Stocks remarked:
377 Rector Place Apt #5A
NEW YORK, NY10280-1534

If you don't follow the above format your mail probably won't be
delivered at all or, at the very best, takes a long time to reach its
destination.

The first five digits of the zip code identify the local mail delivery
office, the next four digits (which are optional) identify a group of
around 15 delivery points. Google maps doesn't handle the extended zip
code, but it gets near enough.

I lived in Atlanta for a year, and the five-digit part of the postcode
was all that anyone used. Unfortunately for geo-location purposes it
covered a rather large area. Indeed, despite being in the suburbs (and
not even the outer suburbs) the nearest Post Office (which was also the
district sorting and delivery office) was a 20 minute drive away!
--
Roland Perry