I've seen a number of posts about this problem and many hours later, I'm still going round and round. Someone answer me this question:
A customer cannot/does not reply to the first automated response. The reply from staff does say you can reply to that email. BUT if you do, it creates a new ticket instead of appending to the original one. If you reply to that ticket and the customer then replies back to you it appends.
The question is - IS THIS SUPPOSED TO WORK THIS WAY?
No matter what I"ve done that's how it works. The problem seems to lie here in tickets.class.php
if(db_query($sql) && ($msgid=db_insert_id())) {
$this->setLastMsgId($msgid);
if(!$newticket){
//Success and the message is being appended to previously opened ticket.
//Alerts for new tickets are sent on create.