Post Offices of Europe 18th – 21st Century

The cursus publicus, established by the Roman Empire to connect all its conquered territories, may be considered to be the ancestor of all modern post offices. Therefore, mail service networks are part of an organization, dating from Antiquity, which is common to the entire European community.
From the 18th century onwards, the French mail service network may be divided into three successive phases. First, the consolidation of the transportation system that was being set up. Second, the development of the system’s ability to deal with increasing traffic (through broader human resources). Thirdly, the diversification of its operations and the development of its technical modernisation.
What was the situation in other European countries? Are there similarities and differences in how their networks were set up and organized? Finally, how did European Post Offices cooperate with each other in spite of their differences?