The F=9 delivery
agent flag causes the MIME message body of a delivered message to be
converted back from either quoted-printable or
base64 into its original 8-bit form. The
F=9 delivery agent flag is effective only if
sendmail was compiled with MIME7TO8 defined
(MIME7TO8).
Conversion works only on single-part MIME messages. If the
Content-Type: header is other than
text/plain, no conversion is done. Otherwise, the
Content-Transfer-Encoding: header is examined. If
the Content-Transfer-Encoding: header type is
base64, conversion is done from
base64 to 8-bit. Otherwise, if the
Content-Transfer-Encoding: header type is
quoted-printable, conversion is done from
quoted-printable to 8-bit. If the
Content-Transfer-Encoding: header type is neither,
no conversion is done.
