[Zope] problem with quoted-printable mine encoded text/html attachments in Zope 2.3

I am sending an email via zope, that consists of a plain text message, followed by an html attachment in quoted-printable encoding. The problem is that it splits the message into line of 72 chars, and it does that in the middle of a url, so in both evolution and communicator images don't show up and links are wrong, but it appear correct in outlook express. I've gotten it to work with 7bit encoding and a content-type of text/html, but from what I've seen html attachment should be in quoted-printable encoding.