Imperial China received diplomatic missions from other places whenever those places decide to send a mission (for example: Japanese missions to Imperial China). These missions were irregular, and were only done in one direction (i.e. to China, and not from China). The sending country would learn more about China during their mission.
The Qing opened their first consulate in Singapore in 1873 (followed by consulates in Hawaii, Cuba, etc.). But before that, how did the Qing keep in contact with other places? How did they get information about other places if they did not send (regular or irregular) diplomatic missions?