Abstract: A rule-based system for utilizing available storage in combination with arbitrary transformations, such as compression or encryption, within an email system is disclosed herein. The system may include an event-based storage of messages in specific tiers of storage based on a subscriber's class-of-service, attributes of the message, or attributes of the attachments. An automated or administrator directed application of storage rules over an existing mailbox or set of mailboxes may also be implemented. A plurality of storage locations may be included in the system, and each may be associated with at least one of a type, protocol, or transformation to be applied.