Change Ticket Subject to notification reply email subject

I’m trying to ‘interface’ RT to another ticketing system which pre-pends it’s own ticket number on reply to our initial email.

Here’s what I’m trying to do…

I create a ticket in RT and I use the email address of the destination ticketing system and RT sends the email.

The remote system receives the email from our RT instance with the subject line of
[Our_System_Name #2213] Problem description blah

The remote then assigns a ticket to us which it Pre-Pends to our Subject line such as
[#VGL-219-77268]: [Our_System_Name #2213] Problem description blah

which it sends back to us,

Our RT processes that incoming email updates the correct ticket in the queue BUT the subject line of the Ticket is not changed to match this new information when our agents click “reply” they must manually Prepend that remote system’s ticket number or the transaction fails and the remote system opens another ticket number to us…

There must be a way to automate this in a Template but I’m not able to find the variable that is the incoming email subject line…

Thx

This should be very easy
Read this https://docs.bestpractical.com/rt/4.4.1/RT/Action/ExtractSubjectTag.html

Thanks - it looks like that’s what I’m after.

Cheers!