Parse the message structure, converting the data. Thus, decode quoted-printable. Target format does not want Base64, decode Base64. Target format does not want binary, encode UUencode. Target format wants UUencode, conversion on this data is completed.
All data is converted according to the target format.
Start converting headers. Remove any MIME-specific headers in the root header. Also add the Mailtool boundary to the boundary string. The second bodypart is a text. Add the Mailtool headers.