Hi I have noticed that mhbuild don't implement header field folding. Specialy for the References field this might cause problems, when you use it to feed a mail build by mhbuild to a tool which checks the line length.
Also I don't get the code. In uip/mhbuildsbr.c:359 a LENERR is handled with die(), but I can't create a testcase for this. Philipp
