Perl MIME:LITE 中文標題 亂碼

Reference:
使用 perl 发送中文邮件标题乱码
Email主旨亂碼 =?Big5?(Q|B)?xxxxxxxxxx ?=

狀況：
用 MIME:LITE 發信，中文標題變成亂碼

解法：
use MIME::Lite;
use MIME::Base64;

$mail_host = "My_SMTP_server";
$mail_from = 'from_address';
$mail_to = 'to_address';
$mail_subject = '=?big5?B?'. encode_base64("繁體中文標題") .'?=';
$mail_body = "Test";

mail_notify();

sub mail_notify {
MIME::Lite->send('smtp', $mail_host, Debug=>0, Timeout=>60);
$msg = MIME::Lite->new(
From     => $mail_from,
To       => $mail_to,
Subject  => $mail_subject,
Type     =>'multipart/mixed',
);
$msg->attach (
Type => 'TEXT',
Data => $mail_body,
) or die "Error adding the text message part: $!\n";
$msg->send();
}