Reject

Used if the customer wrote a follow up and the follow up is rejected (because the ticket is closed and not possible to reopen).

A normal reject auto-response should contain somthing like that:
Thanks for your follow up e-mail

You wrote:
<OTRS_CUSTOMER_EMAIL[6]>

Important: Sorry but we can't process your follow up 
because your ticket is closed. Please create a new ticket.

Have fun with OTRS!

Your OTRS Team