Abstract: A method and system for converting the format of computer mail messages using a dynamic set of conversion routines is provided. In a preferred embodiment, a message format conversion engine uses an updatable registry to access an extensible set of available conversion routines. The registry contains selection information and invocation information for each of the available conversion routines. The selection information in each case describes the classes of messages that the conversion routine is potentially capable of converting. The invocation information comprises information necessary to invoke the conversion routine. When a message is submitted to the conversion engine, the engine reads the selection information stored in the registry. The engine then uses the read selection information to select one of the available conversion routines likely to be capable of converting the message.