1. A computer-implemented method for managing access to electronic documents, the computer-implemented method comprising: at a network device, detecting a request to access a particular electronic document stored on the network device; and in response to detecting the request to access the particular electronic document stored on the network device, applying a document retention policy to the particular electronic document by: determining that the particular electronic document belongs to a particular electronic document retention classification from a plurality of electronic document retention classifications, retrieving document retention policy data for the particular electronic document retention classification, wherein the document retention policy data for the particular document retention classification specifies one or more deletion criteria for the particular document retention classification, determining whether any of the one or more deletion criteria for the particular electronic document retention classification are satisfied, if any of the one or more deletion criteria for the particular electronic document retention classification are satisfied, then causing the particular electronic document to be deleted, if none of the one or more deletion criteria for the particular electronic document retention classification are satisfied, then applying a document security policy to the particular electronic document by: determining that the particular electronic document belongs to a particular document security classification from the plurality of document security classifications, retrieving document security policy data for the particular document security classification, wherein the document security policy data for the particular document security classification specifies one or more access criteria for the particular document security classification, determining, based upon the one or more access criteria for the particular document security classification and one or more attributes of a user associated with the request to access the particular electronic document, whether the user is authorized to access the particular electronic document, and if the user is not authorized to access the particular electronic document, then preventing access to the particular electronic document.