Abstract: A method of filtering junk messages has the steps of generating an implicit code, adding the implicit code to an message to be sent to an addressee, sending the message with the implicit code and a sender's address to the addressee from a sender, and determining whether the implicit code in the message matches a local reference code corresponding to a sender being recorded in an addressee's contact list. The message is correctly received in a normal message box if the implicit code matches the local reference code, otherwise the message is blocked.