Encode::IMAPUTF7 - modification of UTF-7 encoding for IMAP

       IMAP mailbox names are encoded in a modified UTF-7 when names contains international characters outside
       of the printable ASCII range. The modified UTF-7 encoding is defined in RFC2060 (section 5.1.3).

   RFC2060-section5.1.3-MailboxInternationalNamingConvention
       By convention, international mailbox names are specified using a modified version of the UTF-7 encoding
       described in [UTF-7].  The purpose of these modifications is to correct the following problems with
       UTF-7:

       1.  UTF-7  uses  the  "+"  character  for  shifting; this conflicts with the common use of "+" in mailbox
           names, in particular USENET newsgroup names.

       2.  UTF-7's encoding is BASE64 which uses the "/" character; this conflicts with the  use  of  "/"  as  a
           popular hierarchy delimiter.

       3.  UTF-7 prohibits the unencoded usage of "\"; this conflicts with the use of "\" as a popular hierarchy
           delimiter.

       4.  UTF-7  prohibits  the unencoded usage of "~"; this conflicts with the use of "~" in some servers as a
           home directory indicator.

       5.  UTF-7 permits multiple alternate forms to represent the same string;  in  particular,  printable  US-
           ASCII chararacters can be represented in encoded form.

       In modified UTF-7, printable US-ASCII characters except for "&" represent themselves; that is, characters
       with  octet  values  0x20-0x25  and  0x27-0x7e.  The character "&" (0x26) is represented by the two-octet
       sequence "&-".

       All other characters (octet values 0x00-0x1f, 0x7f-0xff, and all Unicode 16-bit octets)  are  represented
       in  modified  BASE64, with a further modification from [UTF-7] that "," is used instead of "/".  Modified
       BASE64 MUST NOT be used to represent any printing US-ASCII character which can represent itself.

       "&" is used to shift to modified BASE64 and "-" to shift back to US- ASCII.  All names start in US-ASCII,
       and MUST end in US-ASCII (that is, a name that ends with a Unicode 16-bit octet MUST end with a "- ").

       For  example,  here  is  a  mailbox   name   which   mixes   English,   Japanese,   and   Chinese   text:
       "~peter/mail/&ZeVnLIqe-/&U,BTFw-"

       Sava Chankov <sava@cpan.org>

       Ricardo Signes <rjbs@semiotic.systems>

       This software is copyright (c) 2005 by Sava Chankov.

       This  is  free  software;  you  can  redistribute  it and/or modify it under the same terms as the Perl 5
       programming language system itself.

perl v5.40.1                                       2025-05-29                              Encode::IMAPUTF7(3pm)

       Encode::IMAPUTF7 - modification of UTF-7 encoding for IMAP

       This library should run on perls released even a long time ago.  It should work on any version of perl
       released in the last five years.

       Although it may work on older versions of perl, no guarantee is made that the minimum required version
       will not be increased.  The version may be increased for any reason, and there is no promise that patches
       will be accepted to lower the minimum required perl.

           use Encode qw/encode decode/;
           use Encode::IMAPUTF7;

           print encode('IMAP-UTF-7', 'Répertoire');
           print decode('IMAP-UTF-7', 'R&AOk-pertoire');

       version 1.07