Royal Mail, the British postal service, has decided to celebrate its 500 years of postal history in 2016. There will be all kind of celebrations around this milestone, like a special exhibition of 500 mail-related items, some special stamps launched in February... You can find all the information in this website.
Also during 2016 Correos, the Spanish postal service, seems to be celebrating its 300th anniversary. I still did not find the website.
Do you know how old the postal services of your country are?