The department was abolished in 1977 and the country's mailing and telegraphing was assumed by the new government-owned company, "Communications Authority of Thailand" (CAT).

Traditionally, messages between the government in Bangkok and provincial outposts had been carried by a herald or by fast boat.

The earliest recorded mail from Bangkok dates back 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 the Bowring Treaty signed between Great Britain and Siam (now Thailand) on 18 April 1855, in response to a demand by expatriate merchants and missionaries.

The company projects total revenue for 2018 at more than 30.8 billion baht with double-digit growth in net profit again.