What does the message source look like?
As the message says, the MIME->CD converter
thinks it has found a Content-type header with a boundary parameter, but
that Content-type is not multipart. A Content-type header for a multipart
mime part might look something like this:
Content-type: multipart/related; boundary="_This_is_the_boundary"
.The declared boundary is then used
to separate the parts within the multipart part -- text parts, image parts,
file attachment parts, etc.
A Content-type header for which the
MIME->CD converter might issue the warning might look like this:
Content-type: text/html; boundary="_This_is_the_boundary"
Because the part's type is text, not
multipart, the converter issues the warning. Note that this is just
a warning and the part should be processed correctly.