1. A method comprising: generating a first communication from syntactically structured phrases for delivery to a user, wherein the first communication forms a first natural language sentence; assessing a behavior of the user in response to the first communication; modifying a phrase frequency distribution for the syntactically structured phrases based, at least in part, on the behavior of the user; and generating a second communication from the syntactically structured phrases for delivery to the user based on the phrase frequency distribution, wherein the second communication forms a second natural language sentence.