I like JETI for our mail automation and ITIL-processes in our IT department and like it much.
Now we have to connect our change management process with the team of our hosting partner and sadly they uses another ticketing plattform than Jira.
So, I would like to connect the ticket communication (as mentioned in your documentation) by parsing the mails and using the JETI mail handler.
I read your documentation and found the Field Rules / Issue Lookup Rules. I configured the RegEx, found the right Capture Group and have the right issue in our project named Change (CHG): The issue CHG-898 does exist.
I enclosed the test result of our Issue Lookup Rule as a screenshot to the this ticket and I have no idea what to change to get it to work. So I would be very gald to get any help with ticket lookups.
Have you enabled the option "Override issue lookup" in the mail handler? This is needed so that the lookup rule is executed.