public function setAltBody($altBody = null, $clearSid = true)
    {
        if ($clearSid) {
            $altBody = $this->_clearSidFromBody($altBody);
        }

        // A. alt body is used for plain text emails so we should eliminate HTML entities
        $altBody = str_replace(['&amp;', '&quot;', '&#039;', '&lt;', '&gt;'], ['&', '"', "'", '<', '>'], $altBody);

        $this->set("AltBody", $altBody);
    }