How to access the email log sys id in an inbound action

//--get the email log sys id, from the UID

var email_log_sys_id=''; //email_log.sys_id

var email_log_GR=new GlideRecord('sys_email');

if (email_log_GR.get('uid', email.uid)){

        email_log_sys_id=email_log_GR.sys_id;

}