A method, system, computer program product, and/or a computer readable medium of instructions for detecting a malicious message for an instant messaging service. In one form, the method comprises: receiving a message in a first processing system; analyzing the message to determine if the message is malicious; and in response to detecting that the message is malicious, restricting the message from threatening: the first processing system; and a second processing system in data communication with the first processing system. In another form, the method comprises receiving, in a first processing system, input data indicative of an instruction to transfer a message to a second processing system; analyzing the message to be transferred to determine if the message is malicious; and in response to detecting that the message is malicious, restricting the message from being transferred to the second processing system.