1. A method comprising: receiving, at an instant messaging server, an instant message from a sender, wherein the instant messaging server is a real-time messaging server, and wherein the instant message is a real-time message; transmitting, from the instant messaging server to the sender in response to the received instant message, a challenge packet that includes a challenge and encrypted challenge parameters that comprise a server identifier that uniquely identifies the transmitting instant messaging server and a challenge identifier that uniquely identifies the challenge within a challenge library and a challenge answer that indicates a correct response to the challenge; and wherein, after the challenge packet is transmitted to the sender, any state related to the received instant message and the challenge packet and the encrypted challenge parameters is not retained by the instant messaging server.