Email header <message-id> customize

For non SMTP e-mails sent, if you add the line $mail->setMessageId(); before @$mail->send(); it will send an e-mail with piwik url in Message-Id e-mail header.

eg:

    // send email with new password
    $mail = new Mail();
    $mail->addTo($email, $login);
    $mail->setSubject(Piwik::translate('Login_MailTopicPasswordChange'));
    $bodyText = str_replace(
            '\n',
            "\n",
            sprintf(Piwik::translate('Login_MailPasswordChangeBody'), $login, $ip, $url)
        ) . "\n";
    $mail->setBodyText($bodyText);

    $mail->setFrom($this->emailFromAddress, $this->emailFromName);

    $replytoEmailName = Config::getInstance()->General['login_password_recovery_replyto_email_name'];
    $replytoEmailAddress = Config::getInstance()->General['login_password_recovery_replyto_email_address'];
    $mail->setReplyTo($replytoEmailAddress, $replytoEmailName);
$mail->setMessageId();
    @$mail->send();

Message-Id will be shown
Message-Id: < ...@piwik.url.com >
instead
Message-Id: < ...@server.com >

It will be useful for severs sharing several piwik installations.