Comment 1 for bug 265907

I also encountered that bug once at a site of a friend.
Take a look at Mailman/Bouncers/Postfix.py
and especially the line with
       boundary = msg.getparam('boundary')
this can result in boundary being "None"
which is then not treated properly.
So add the following check below this with
the correct indentation:
        if not boundary:
                        return None

If I remember correctly this was handled completely differently
in Mailman 2.1 so I believe that this bug is limited to
Mailman 2.0.x.