1. A computer-implemented method, comprising: grouping a corpus of outgoing communications sent by a user using one or more computing devices into a plurality of clusters, wherein each outgoing communication of the corpus is grouped into a cluster based on one or more attributes of a context of the user when the outgoing communication was sent, and wherein the one or more attributes of the context of the user when the outgoing communication was sent are determined based on one or more signals provided by a computing device operated by the user when the outgoing communication was sent; classifying one or more segments of each outgoing communication of a particular cluster as fixed in response to a determination that a count of occurrences of the one or more segments across the particular cluster satisfies a criterion; classifying one or more remaining segments of each outgoing communication of the particular cluster as transient; generating, based on sequences of classified segments associated with each communication of the particular cluster, an outgoing communication template that is usable to automatically populate at least a portion of one or more draft outgoing communications being prepared by the user; determining, based on one or more interactions between the user and the same computing device or a different computing device, that the user is preparing a subsequent outgoing communication; selecting a particular outgoing communication template from a plurality of outgoing communication templates, wherein the selecting is based on one or more attributes of a current context of the user that are determined based on one or more signals provided by the same computing device or by the different computing device; and applying the particular outgoing communication template to automatically populate at least a portion of the subsequent outgoing communication being prepared by the user with content from the particular outgoing communication template.
5. The computer-implemented method of claim 1 , wherein the one or more attributes of the context of the user when the outgoing communication was sent include geographic coordinates of the user sensed by a mobile computing device operated by the user to send the outgoing communication.