In the mid-1990's, I requested information from a major multinational corporation (IBM) that had a significant presence in my country. They somehow managed to mangle the six characters of a Canadian postal code, which alternates between letters and digits, into a five digit zip code. Making it even more perplexing, the envelope was addressed by hand and came from New York state. Some Americans seem to think that the rest of the world is a mirror of them, and will go through unusual contortions to maintain that belief. (To be fair: there is another level above that which is Anglo-centric, which allows for just enough variation between English speaking nations.)

I have seen websites that more-or-less takes the author's advice though. They are country specific. They are backed by the postal system's database. They present a list of addresses that match up with the postal code. They do not work very well when a particular address does not have a postal code. And yes, that happens.