Processes and techniques for reducing spam over instant messaging (SPIM) are described. In one implementation, the number of open instant messaging threads (“chat threads”) that a specific user can have at a given time is limited to prevent a potential spimmer from flooding instant messaging users...http://www.google.com.tw/patents/US7779079?utm_source=gb-gplus-share專利 US7779079 - Reducing unsolicited instant messages by tracking communication threads
