1. A method comprising: receiving an electronic document; analyzing, using at least one processor, the electronic document to extract a number of first attributes from the electronic document, the number of first attributes selected from a first attribute set; obtaining a first classification output for the electronic document based upon the number of first attributes extracted from the electronic document; if the first classification output for the electronic document is above a first threshold, withholding delivery of the electronic document; if the first classification output for the electronic document is below the first threshold, analyzing the electronic document to extract a number of second attributes from the electronic document, the number of second attributes selected from a second attribute set, and obtaining a second classification output for the electronic document based upon the number of second attributes extracted from the electronic document; if the second classification output for the electronic document is above a second threshold, withholding delivery of the electronic document; and if the second classification output for the electronic document is below the second threshold, delivering the electronic document.