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properly deal with RFC-1522 encoded words

MIME::AltWords - properly deal with RFC-1522 encoded words


MIME::AltWords - properly deal with RFC-1522 encoded words


The Perl module the MIME::AltWords manpage is recommended for encoding and decoding MIME words (such as =?ISO-8859-2?Q?_=E1ll_e=E1r?=) found in e-mail message headers (mostly Subject, From and To).

the MIME::AltWords manpage is similar to the MIME::Words manpage in the MIME::Tools manpage, but it provides an alternate implementation that follows the MIME specification more carefully, and it is actually compatible with existing mail software (tested with Mutt, Pine, JavaMail and OpenWebmail). the MIME::AltWords manpage extends the functionality of the MIME::Words manpage (version 5.420) by adding more functions and more options to existing functions. The original interface is changed in an upward-compatible way.

Before reading further, you should see the MIME::Tools manpage to make sure that you understand where this module fits into the grand scheme of things. Go on, do it now. I'll wait.

Ready? Ok...

    use MIME::AltWords qw(:all);   


    ### Decode the string into another string, forgetting the charsets:

    $decoded = decode_mimewords(

          'To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <>',



    ### Split string into array of decoded [DATA,CHARSET] pairs:

    @decoded = decode_mimewords(

          'To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <>',



    ### Encode a single unsafe word:

    $encoded = encode_mimeword("\xABFran\xE7ois\xBB");


    ### Encode a string, trying to find the unsafe words inside it: 

    $encoded = encode_mimewords("Me and \xABFran\xE7ois\xBB in town");


Fellow Americans, you probably won't know what the hell this module is for. Europeans, Russians, et al, you probably do. :-).

For example, here's a valid MIME header you might get:

      From: =?US-ASCII?Q?Keith_Moore?= <>

      To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <>

      CC: =?ISO-8859-1?Q?Andr=E9_?= Pirard <>

      Subject: =?ISO-8859-1?B?SWYgeW91IGNhbiByZWFkIHRoaXMgeW8=?=



The fields basically decode to (sorry, I can only approximate the Latin characters with 7 bit sequences /o and 'e):

      From: Keith Moore <>

      To: Keld J/orn Simonsen <>

      CC: Andr'e  Pirard <>

      Subject: If you can read this you understand the example... cool!


encode_mimewords RAW, [OPTS]
Function. Given a RAW string, try to find and encode all ``unsafe'' sequences of characters:

    ### Encode a string with some unsafe "words":

    $encoded = encode_mimewords("Me and \xABFran\xE7ois\xBB");

Returns the encoded string. Any arguments past the RAW string are taken to define a hash of options:

Encode all unsafe stuff with this charset. Default is 'ISO-8859-1', a.k.a. ``Latin-1''.

The encoding to use, "q" or "b". The default is "q".

Name of the mail field this string will be used in. Currently ignored.

Note: this is a stable, tested, widely compatible solution. Strict compliance with RFC-1522 (regarding the use of encoded words in message headers), however, was not proven, but strings returned by this function work properly and identically with Mutt, Pine, JavaMail and OpenWebmail. The recommended way is to use this function instead of encode_mimeword() or encode_mimewords in the MIME::Words manpage.

encode_mimeword RAW, [ENCODING], [CHARSET]
Function. Encode a single RAW ``word'' that has unsafe characters. The ``word'' will be encoded in its entirety.

    ### Encode "<<Franc,ois>>":

    $encoded = encode_mimeword("\xABFran\xE7ois\xBB");

You may specify the ENCODING ("Q" or "B"), which defaults to "Q". You may specify the CHARSET, which defaults to iso-8859-1.

decode_mimewords ENCODED, [OPTS...]
Function. Go through the string looking for RFC-1522-style ``Q'' (quoted-printable, sort of) or ``B'' (base64) encoding, and decode them.

In an array context, splits the ENCODED string into a list of decoded [DATA, CHARSET] pairs, and returns that list. Unencoded data are returned in a 1-element array [DATA], giving an effective CHARSET of undef.

    $enc = '=?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <>';

    foreach (decode_mimewords($enc)) {

        print "", ($_[1] || 'US-ASCII'), ": ", $_[0], "\n";


In a scalar context, joins the ``data'' elements of the above list together, and returns that. Note: this is not information-lossy, it sanitizes the returned string to use a specific, single charset, either specified using the Charset option, or autodetecting one (ISO-8859-1, ISO-8859-2 or UTF-8) which can accomodate all characters. In case of charset autodetection, get_best_decode_charset(ENCODED) can be used to query the charset autodetected.

You might want to see unmime in the MIME::WordDecoder manpage as an alternate of the MIME::AltWords::encode_mimewords manpage.

In the event of a syntax error, $@ will be set to a description of the error, but parsing will continue as best as possible (so as to get something back when decoding headers). $@ will be false if no error was detected.

Any arguments past the ENCODED string are taken to define a hash of options:

Name of the mail field this string came from. Currently ignored.


Exports its principle functions by default, in keeping with the MIME::Base64 manpage and the MIME::QuotedPrint manpage.

Doesn't depend on the MIME::Words manpage or the MIME::Tools manpage. All the shared code is copied to the MIME::AltWords0 manpage, which is bundled.

See also for the previous version of the MIME::AltWords manpage integrated into the Sympa 4 mailing list software.


the MIME::AltWords manpage was written by Péter Szabó ( in 2006, and it has been uploaded to CPAN on 2006-09-27.

the MIME::AltWords manpage uses code from the MIME::Words manpage (in the file lib/MIME/ and it uses documentation from the MIME::Words manpage (in the files lib/MIME/ and lib/MIME/

Here is the original author and copyright information for the MIME::Words manpage.

Eryq (, ZeeGee Software Inc ( David F. Skoll (

All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

Thanks also to...

      Kent Boortz        For providing the idea, and the baseline 

                         RFC-1522-decoding code!

      KJJ at PrimeNet    For requesting that this be split into

                         its own module.

      Stephane Barizien  For reporting a nasty bug.


See $VERSION in lib/MIME/ .