How to send postcards from Hong Kong to the mainland?

just add the address directly and put a stamp on it .. the address format is the same as that in the mainland. You can write simplified Chinese characters or traditional Chinese characters. There is no regulation. The staff can understand it, too. The working hours of post offices in every place are not uniform. They are basically from 9: 3 am to 5: pm. (Monday to Friday) Almost all of them are closed on weekends. There are only three jobs. The General Post Office, No.2 Recreation Plaza, Central, Hong Kong, is from 9: a.m. to 5: p.m. The Airport Post Office, No.1 Changhang Road, Lantau Island, is located at 7T82, the passenger terminal building of Hong Kong International Airport, and the ground floor and the first floor of Tsim Sha Tsui Post Office, No.1 Middle Road, Kowloon, are from 9: a.m. to 2: p.m. (open on Sundays and closed on public holidays