sendmail is not 8-bit-clean. It destroys bytes 128 through 159 in
message headers. It has to be fixed (I explained the easy fix to the
sendmail author _four years ago_) or replaced with better MTAs (which
is gradually happening).
Lilly is completely missing the point when he says that sendmail doesn't
hurt any messages allowed by RFC 2822. The goal here is to allow _more_
messages---specifically, UTF-8 messages.
---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago