1. A method comprising: determining one or more probabilities that a document belongs to one or more of a plurality of predefined categories; determining whether at least one of the one or more probabilities satisfies a first predetermined threshold; causing the document to be used in data loss detection when at least one of the one or more probabilities satisfies the first predetermined threshold; if at least one of the one or more probabilities does not satisfy the first predetermined threshold, determining, by a processor, whether at least one of the one or more probabilities satisfies a second predetermined threshold specific to a source of the document; and causing the document to be used in data loss detection when at least one of the one or more probabilities satisfies the second predetermined threshold.