Definition of open-door policy:
(n) :
(idiomatic, politics) A governmental policy of encouraging immigration or of permitting increased access by foreigners for purposes of tourism, trade, investment, etc.
(n) :
(idiomatic, management, politics) A policy or usual practice, by a person in authority, of permitting subordinates or constituents to visit his or her office unannounced and at any reasonable time for the purpose of discussing matters of concern.