src/MimeMailer/MimeMessage.php
public function setReplyTo($mail = '', $name = null)
    {
        if (strlen($mail) && Helper::isEmail($mail)) {
            if (!empty($name)) {
                $_m = Helper::mailTagger($mail, $name);
            } else {
                $_m = $mail;
            }
            $this->getMailer()->setRegistry('Reply-To', $_m, 'headers');
        }
        return $this;
    }
public function setReplyTo($mail = '', $name = null)
    {
        if (strlen($mail) && Helper::isEmail($mail)) {
            if (!empty($name)) {
                $_m = Helper::mailTagger($mail, $name);
            } else {
                $_m = $mail;
            }
            $this->getMailer()->setRegistry('Reply-To', $_m, 'headers');
        }
        return $this;
    }
Set Reply-To header field

@param string/array $mail The email address to add, or an array of name=>email pairs
@param string/bool $name The name to show for the email address if there is just one
@return self