A system (140) prevents the spread of viruses in a network (100). The system (140) receives a hash value from a remote device (130), compares the hash value to a group of hash values associated with data messages including viruses, and generates a first message when the hash value matches one of the group of hash values. The first message instructs the remote device (130) to discard a received data message. The system (140) also generates a second message when the hash value does not match one of the group of hash values. The second message instructs the remote device (130) to forward the received data message to a user of the remote device (130).