"One of the most interesting ways to know about a country and its history is through stamps and no other better way than to check each
country's postal administration. Given below is the list of all known and verified postal bureaus as approved by Universal Postal Union
as well as new countries which are yet to be recognized. Most of the postal bureaus have a separate section on Philately."
Dead:
Stampville.com (whose structure was followed for this section)
Philately.com (Postal Authority street address data no longer provided but given freely at the time and was the original data with which I started in 1998.)
21 members (national postal services), handling 65% of the World's
postal traffic.
c.2014 : "IPC members (cc) represent postal operators from Europe, North America and the Asia-Pacific region. Collectively, their operations deliver 80% of global mail volumes – more than 336bn letters each year."
A web site providing links to "address management on the web", including to
postal authority sites, postal code sites and companies offering address management services.
Post Insight.com (in English) - Check this page regularly for information about changes in postal
services throughout the World.