1. A method for detecting content similarity in email documents comprising: generating a first token value for each of a plurality of character sequences of a first email document; selecting a first subset of the plurality of character sequences based on the first token values, wherein the first subset does not include all of the plurality of character sequences of the first email document; generating one or more hash values corresponding to the selected first subset of character sequences; generating a second token value for each of a plurality of character sequences of a second email document; selecting a second subset of the plurality of character sequences based on the second token values, wherein the second subset does not include all of the plurality of character sequences of the second email document; generating one or more hash values corresponding to the selected second subset of character sequences; and comparing the one or more hash values corresponding to the selected first subset with the one or more hash values corresponding to the selected second subset.