One or more techniques and/or systems are provided for defining a message behavior profile for a sender, which may be used to categorize messages from the sender. A message behavior profile may be defined based upon, for example, message distribution behavior of the sender (e.g., volume, frequency, variance in content amongst messages sent to recipients, etc.); recipient interactions with messages from the sender (e.g., message read rates, message response rates, etc.); unsubscription options comprised within messages from the sender; and/or other factors. In this way, the message behavior profile and/or features extracted from a message may be used to categorize a message from the sender (e.g., newsletter, commercial advertisements, alert, social network etc.). Categorized messages may be organized into folders, displayed or hidden within views, and/or processed based upon their respective categorizations.