I think we all understand the difference between the stream of packets comprising an application message and the message itself. What we don't understand is what, if anything, jfcm may be proposing for OPES. I believe he is trying to find a way to use OPES to keep SMTP messages a logical "streams", even when almost the entire message must be available to an OPES service. This does not seem to affect the OPES charter or architecture. It's an application of OPES, and an example of how, given enough state, anything can be turned into a stream processing model.
Hilarie