The conversion channel performs arbitrary body part by body part conversions on messages flowing through PMDF. Any subset of PMDF traffic can be selected for conversion and any set of programs or command procedures can be used to perform conversion processing. (PMDF's native conversion facilities are fairly limited, so the ability to call external converters is crucial.) A special database is consulted to choose an appropriate conversion for each body part.

For instance, third party document convertors or virus scanning software may be hooked in for automatic execution via the conversion channel. Or sites may develop their own custom applications to hook in via the conversion channel.