1. A message broadcast system, comprising: a processor; a memory coupled to the processor; and a broadcast server stored in the memory and executable on the processor, wherein the broadcast server is adapted to receive a message for a plurality of subscribers and a desired number of suitable responses from a sender; broadcast the message to subsets of the plurality of subscribers in a first round of waves; if the sender does not receive the desired number of suitable responses, rebroadcast the message to subsets of substantially the same plurality of subscribers in a second round of waves; and wherein broadcasting the message to subsets of the plurality of subscribers in a round of waves comprises periodically sending the message to two or more subscribers until substantially all of the plurality of subscribers receives the message.