If the mime attachment has a Content-Type of text/XXXX and doesn't contain a Content-Disposition in the Mime-Part Header
the content of the attachment is added to the body.
--=-=PVvSFEwmDdvI9R=-=
Content-Type: text/comma-separated-values;
charset="us-ascii";
name="test.csv"
Content-Transfer-Encoding: 7bit
Content-ID: <blubber>
1,2,3
--=-=PVvSFEwmDdvI9R=-=--

