A “message broker” personalizes messages based on the recipient's estimated “privacy sensitivity.” By carefully estimating the sensitivity, the message broker can achieve the advantages of personalized messaging without incurring the disadvantages of offending or scaring away the recipient. In a first set of embodiments, messages are sent to a recipient, and information about the recipient's responses is collected and analyzed. The sensitivity level of the recipient is estimated based on this collected information. In a second set of embodiments, messages are sent that include an offer in which an incentive will be given to the recipient in exchange for allowing a certain type of access to specific information associated with the recipient. In a third set of embodiments, the message broker sends messages that request information associated with the recipient, but the messages do not include explicit offers to give incentives in exchange for the information.