use strict;
use MIME::WordDecoder;

sub decode_words {
   my $value = shift || "";
   my $wd = default MIME::WordDecoder;

   eval q{require Encode; $value = Encode::decode('MIME-Header', $value);}; # falls kein Enocde vorhanden

   $wd->handler("BIG5" => "KEEP");

   $wd->handler("WINDOWS-1250" => "KEEP");
   $wd->handler("WINDOWS-1251" => "KEEP");
   $wd->handler("WINDOWS-1252" => "KEEP");
   $wd->handler("WINDOWS-1253" => "KEEP");
   $wd->handler("WINDOWS-1254" => "KEEP");
   $wd->handler("WINDOWS-1255" => "KEEP");
   $wd->handler("WINDOWS-1256" => "KEEP");
   $wd->handler("WINDOWS-1257" => "KEEP");
   $wd->handler("WINDOWS-1258" => "KEEP");    

   my $decoded = "";
   eval { $decoded = $wd->decode($value); };
    
   my $retval = $decoded ? $decoded : $value;    
   return ($retval);
}

my $subject = "=?iso-8859-1?Q?test_mit_3_Anh=E4ngen_01?=";

print decode_words($subject);

use MIME::Words ();

sub encode_words {
   my $value = shift;
   return ($value ? MIME::Words::encode_mimewords($value) : "");
}

print encode_words("test_mit_3_Anhängen");

test_mit_3_=?ISO-8859-1?Q?Anh=84ngen?=

test_mit_3_=?ISO-8859-1?Q?Anh=84ngen?=