1. A method comprising: obtaining an email that is sent from a sender to a recipient; and in response to determining that no direct relationship exists between the sender and the recipient, and instead that an indirect relationship exists between the sender and the recipient: determining, based at least in part on the indirect relationship, a spam probability associated with the email by evaluating statistical information regarding historical electronic interactions associated with the sender and the recipient, wherein the historical electronic interactions associated with the sender and the recipient includes historical electronic interactions from one or more non-email applications, and wherein the statistical information includes information associated with a frequency of interaction between the sender and the recipient; and classifying the email according to the identified spam probability, wherein the direct relationship is defined by a historical bi-directional interaction between the sender and the recipient in which the recipient has previously accepted and replied to at least one electronic message sent by the sender, and wherein the indirect relationship is defined only by a historical unidirectional interaction between the sender and the recipient in which the recipient has not previously accepted and replied to any email messages sent by the sender.