1. A method, performed by a server having one or more processors and memory storing one or more programs for execution by the one or more processors, comprising: at the server: receiving from a client device a request, the request comprising a request for message content from a plurality of email messages in a conversation thread; and responding to the request by: identifying the message content from the plurality of email messages in the conversation thread; identifying a plurality of candidate authors in accordance with a plurality of message authors in the conversation thread identified by the request; obtaining a plurality of qualifying social network posts by the plurality of candidate authors, the plurality of qualifying social network posts satisfying predefined criteria, wherein the plurality of qualifying social network posts are distinct from the conversation thread and distinct from email messages and include social network posts of a plurality of distinct authors; selecting a subset of the plurality of qualifying social network posts, including a plurality of social network posts by a plurality of distinct candidate authors of the plurality of candidate authors; and preparing the selected subset of the plurality of qualifying social network posts and the message content for display at the client device.