Linux Blog

Encode::MIME::Header

Section: Perl Programmers Reference Guide (3)
Updated: 2001-09-21
Index Return to Main Contents
 

NAME

Encode::MIME::Header -- MIME 'B' and 'Q' header encoding  

SYNOPSIS

    use Encode qw/encode decode/; 
    $utf8   = decode('MIME-Header', $header);
    $header = encode('MIME-Header', $utf8);

 

ABSTRACT

This module implements RFC 2047 Mime Header Encoding. There are 3 variant encoding names; "MIME-Header", "MIME-B" and "MIME-Q". The difference is described below

              decode()          encode()
  ----------------------------------------------
  MIME-Header Both B and Q      =?UTF-8?B?....?=
  MIME-B      B only; Q croaks  =?UTF-8?B?....?=
  MIME-Q      Q only; B croaks  =?UTF-8?Q?....?=

 

DESCRIPTION

When you decode(=?encoding?X?ENCODED WORD?=), ENCODED WORD is extracted and decoded for X encoding (B for Base64, Q for Quoted-Printable). Then the decoded chunk is fed to decode(encoding). So long as encoding is supported by Encode, any source encoding is fine.

When you encode, it just encodes UTF-8 string with X encoding then quoted with =?UTF-8?X?....?= . The parts that RFC 2047 forbids to encode are left as is and long lines are folded within 76 bytes per line.  

BUGS

It would be nice to support encoding to non-UTF8, such as =?ISO-2022-JP? and =?ISO-8859-1?= but that makes the implementation too complicated. These days major mail agents all support =?UTF-8? so I think it is just good enough.

Due to popular demand, 'MIME-Header-ISO_2022_JP' was introduced by Makamaka. Thre are still too many MUAs especially cellular phone handsets which does not grok UTF-8.  

SEE ALSO

Encode

RFC 2047, <http://www.faqs.org/rfcs/rfc2047.html> and many other locations.


 

Index

NAME
SYNOPSIS
ABSTRACT
DESCRIPTION
BUGS
SEE ALSO