Mr. Curtis,
I'm sorry I don't know much about this, but I wanted to do anything I
could and hopefully learn more about this important question.
There is a large web site based in Tucson that has their own
distributed email system set up in a very similar matter to what you
described. Although I know nothing about it, I do recall that their lan
administrator told me that the important key to this was your email
server's ability to handle the "ETRN" command. For all I know, "ETRN" is
a standard part of the smtp command set; alternatively it could be a
Microsoft function, and may not work on the MIPS at all.
I realize this wasn't much help, but if you don't find any easier
answers, maybe it will point you in the right direction. I hope you post
the outcome of your query here, as I've had similar requests from two
companies which ultimately did not become customers due to my lack of
support for this particular hack!