This study investigated how content and context features of headlines drive selective exposure when choosing between headlines of a monthly e-mail health newsletter in a naturalistic setting over a period of nine months. Study participants received a monthly e-mail newsletter and could freely open it and click any headline to read the accompanying article. In each e-mail newsletter, nine headlines competed with each other for selection. Textual and visual information of the headlines was content-analyzed, and clickstream data on the headlines were collected automatically. The results showed that headlines invited more frequent audience selections when they provided efficacy-signaling information in an imperative voice, when they used a moderate number of negative emotion words, when they presented negative thumbnail images while mentioning cancer or other diseases, and when they were placed higher in position.