.TH MAIL-TRANSCODE 1 2015-05-01 "" "User Commands"
.SH NAME
mail-transcode \- convert between quoted-printable, base64 and binary
.SH SYNOPSIS
.B mail-transcode
.RB [ -v ]
.RB [ -q ]
.RB [ -b ]
.RI [ file ]
.SH DESCRIPTION
.B mail-transcode
takes as input an e-mail message and outputs the same message with any
parts that were encoded as `quoted-printable' or `base64' decoded and
re-labeled as `binary'
.PP
With option -q or -b it does the reverse: encode any `binary' parts as
`quoted-printable' or `base64'.
.PP
In other words, a message (or any part of a message) labeled with the header
`Content-Transfer-Encoding: quoted-printable' or
`Content-Transfer-Encoding: base64' is turned into a message with
`Content-Transfer-Encoding: binary', or vice-versa.
.PP
.B mail-transcode
reads from the given
.I file
or from standard input. The input must be structured as a single
e-mail message (possibly a MIME Multipart message), i.e., it must
consist of headers followed by a body. An empty line separates the
headers from the body.
.PP
MIME Multipart messages are handled by decoding/encoding each part
separately. Each part may itself be multipart, and so on, recursively.
.PP
Note that decoding does not yield a valid e-mail message: The
content-transfer-encoding `binary' is defined by RFC 2045, but it may
not actually be used in messages sent over the Internet. It is only
meant for local processing.
.PP
E.g.,
.BR mail-transcode
can be used to decode an e-mail message before processing it with a
local program that cannot handle `quoted-printable' and `base64'.
Afterwards,
.B "mail-transcode -q"
or
.B "mail-transcode -b"
can be used to re-encode the message to a form that is valid for
sending.
.SH OPTIONS
.TP
.B -q
Causes
.B mail-transcode
to encode rather than decode messages. It looks for message parts
labeled as `binary' and converts them to `quoted-printable'.
.TP
.B -b
Similar to
.BR -q ,
except that it encodes binary parts as `base64'.
.TP
.B -v
Print version number and exit.
.PP
If both
.B -q
and
.B -b
are given, the last one specified wins.
.SH BUGS
.B mail-transcode
does not fully parse the mail headers and could misinterpret them if
future standards add extensions. In particular, it does not check the
MIME version (currently `MIME-Version: 1.0').
.SH "EXIT STATUS"
.B mail-transcode
returns 0 on succes, non-zero if an error occurred.
.SH AUTHORS
Bert Bos <bert@w3.org>
.SH SEE ALSO
RFC 2045,
.BR formail (1),
.BR qprint (1),
.BR base64 (1)