2. The method of claim 1 , wherein testing the responsiveness of each group to different message content comprises testing the responsiveness of each group to offers of different products to identify a best product for each group.
3. The method of claim 2 , wherein, after a best product for each group is identified, testing the responsiveness of each group to certain vocabularies by sending test messages to at least a subset of users in each group that include an offer for the best product for the group and the certain vocabularies.