The present invention is directed to systems and methods for detecting and preventing the delivery of unsolicited communications. A communication transmitted over a communications network is received and analyzed by a system processor. The system processor can extract attributes from the communication and compare extracted attributes to information stored in a system data store. In processing the communication, the system processor may assign a confidence level) a trust level, or other indicia of content. The results of that processing, analysis, and comparison can be propagated to one or more upstream computers in the path from the communication's origin to its destination. Such one or more upstream computers are identified from within the content of the communication, the header of the communication and/or the transfer protocol interactions in receiving the communication. The identified computers are authenticated to limit forgery. The upstream computers receiving the propagated information can selectively apply the information to reduce the flow of communications exhibiting the same threat and/or undesirable characteristics.