#!/usr/local/bin/perl5.8.5

use strict;
use MIME::WordDecoder;

my $field='From: =?koi8-r?B?7s/Xb2PUdSDT1NLBeG/Xwc7J0Q==?= <m2z19uyn1b@rrpa.com>';
my $decoded = unmime( $field );
print $decoded