Would be lovely to know more. So, this customer doesn't want an acknowledgement, but insists on one? An acknowledgement of.. what?
I speculate that there're two possible acknowledgments here:
1) "I received your XML";
2) "I successfully process-etc-ed it".

If that is so, de-coupling the code into to parts:
1) getting the client data;l
2) processing it asynchronously

would do?
(you'll probabaly still have to add 
if($customer is not in $my_piss_off_list) {
 only_notify_once...}

[download]
., but that'ok?

In reply to Re: Detecting early termination by client by Mabooka-Mabooka
in thread Detecting early termination by client by enemyofthestate

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