Erik Soderholm) provided me with source code that does pretty much
exactly what I want (well listens to a <protname>% thing from mail and
does something with it).
Glad to hear you got what you need. Maybe I shouldn't mention it right
now, but this is only half the job. This part will handle the outgoing
(MAIL-11 -> FIDOnet) part, but you'll also need to write another program
that runs as a detached system process ("daemon" to you Un*x guys) that
listens for incoming FIDOnet mail and then dumps it into MAIL-11 (presumably
using the MAIL$ API routines). It's not really hard, but it's another piece
that you'll need.
What (or rather who) is still on FIDOnet these days?
Bob