This is a survey of the postal history and postage stamps of Thailand.
Postage stamps and postal history of Thailand Wikipedia
Before Siam issued its first stamp, there was a limited mail service, mainly for the royal family. Domestic mail travelled by messengers while international mail travelled by steamboat to post offices in nearby countries, such as the Straits Settlements.
The earliest recorded mail from Bangkok dates back only to 1836 when American missionary Dan Beach Bradley sent a letter to his father in a stampless cover. The British Consular Post Office in Bangkok was established by Great Britain in 1858 as a consequence of a treaty signed between Great Britain and Siam (now known as Thailand) on 18 April 1855, and in response to a demand by expatriate merchants and missionaries. It ceased to provide service on 1 July 1885, the day Siam joined the Universal Postal Union and started its own international postal service. During that time most of the mail from Bangkok was sent by diplomatic pouch to Singapore for forwarding. Thus most such mail has a Singapore cancel.
Siam issued its first stamp, the Solot Series, on 4 August 1883.