I am using IIS7 (WS2000R2).

I have a Perl script initiated by a web page button action which then initiates a child Perl process to run another script.
The child process takes a variable amount of time to run (depending upon the user's choices in my form).

When the child process duration exceeds about 20 minutes, the parent process expires and the child continues.

This is a problem because the parent still has work to do after the child terminates: it needs to prepare and send an email.

I have already tried to tweak several settings in IIS but none of them seem to alter the time at which the parent expires.
I have amended the following application pool settings:

Idle Time-out (now 60 minutes)
Ping Enabled (true)
Ping Maximum Response Time (seconds) (now 10000)
Shutdown Time Limit (seconds) (now 10000)

I also tried amending the specific web site setting for Connection Limits -> Connection Time-out (seconds) without any success (now back to the default 120s).

Is this a problem I can solve with IIS settings or should I just enhance my child script to do the final tasks?