1. A method comprising: identifying, by a computing device, a policy that protects use-restricted content, the use-restricted content stored in a tabular structure of source data comprising a plurality of data elements in a plurality of columns and a plurality of rows, wherein the policy identifying the use-restricted content is stored separately from the user-restricted content; searching, based on the policy, text in a message for the use-restricted content; identifying a violation of the policy when detecting fragments in the message that match one or more of the plurality of data elements of the use-restricted content from one or more of the plurality of columns and one or more of the plurality of rows within the tabular structure; and specifying, in a report of the violation: the detected fragments in the message that match the one or more data elements of the use-restricted content from the one or more columns and the one or more rows within the tabular structure, and the one or more columns within the tabular structure that contain the data elements matching the detected fragments in the message.