Show parts with Content-ID of multipart/mixed as attachments

The multipart/mixed should behave differently than multipart/related,
because subparts of multipart/mixed are not meant to reference each
other by default, thus the subparts should be shown as attachments.
This was reported at https://bugzilla.redhat.com/show_bug.cgi?id=947409

0 files changed, 0 insertions, 0 deletions