A method for determining predictive response time for electronic mail across enterprise communication systems is described. In particular, the method includes collecting and subsequently analyzing communications of a particular recipient in order to determine a probability of a sender receiving a response from the recipient. In the event a response is probable, the method also determines a time frame when a response may be sent. In situations where the recipient is non-responsive, the method also provides a list of alternate recipients that the sender can communicate with, whereby the alternate recipients are more responsive than the original recipient.