If {HEAD ~ a mailer} wants to send {TAIL ~ advance notice} to a recipient that a mailpiece has been sent to the recipient, the mailer can choose this option automatically and use a unique mailpiece ID as an identifier of the upcoming mailpiece.  
wants to send
If { HEAD ~ a mailer } wants to send { TAIL ~ advance notice } to a recipient that a mailpiece has been sent to the recipient , the mailer can choose this option automatically and use a unique mailpiece ID as an identifier of the upcoming mailpiece .
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH