Patent ID: 7693945

Claim:
A computer implemented method for filtering emails on a server system having one or more processors and memory storing one or more programs for execution by the one or more processors, comprising: receiving an email to a recipient from a sender; identifying a spam probability of the email based at least in part on historical communication activity data between the recipient and the sender, wherein the historical communication activity data includes information from an email application and one or more non-email applications, the one or more non-email applications including at least one of: an instant messaging application, a file-sharing application, and a collaboration application; wherein identifying the spam probability further comprises: tracking network characteristics for the email, the tracked network characteristics including one or more of: network traffic volume per unit of time and network traffic burstiness, and comparing tracked values of the tracked network characteristics for the email to known values for email from trusted or untrusted sources; and classifying the email according the identified spam probability.