Here is the unicode patch which I found in the
mailmanager repository. I'm not sure what license it is
under. You'll have to dig in deeper to make sure. I
found it at this address:
They seem to be doing some restructuring in that
repository, so look around for the exact location.
The patch seems to work for me. I've enabled Unicode
support in my connection, but is still running my zope
website in latin1, and it's converting as it should. I
haven't done thorough testing. But I guess you know how
to do that. :)
PS: Uploading the entire tarball of the patched
distribution. Rip out the changes from it. Didn't have
time to run the diff myself.