When data is stored on a computer, or subsequently, originator preferences relating to the data are stored in a database, for example in a network. When another user subsequently makes a request for processing of the received data, or a modified copy of the data, it is determined whether the requested processing is consistent with any stored originator preferences, and the requested processing is permitted only if it is consistent with the stored originator preferences. The preferences may relate to saving, copying or retransmitting the data. The originator may be notified of any processing operations that are carried out.