At work, we use Request Tracker for handling trouble tickets. By and large, people submit tickets via email, which usually works great. There are cases where someone will email the ticketing system and Cc other people. Those other people then Reply All and end up generating a new ticket. There’s a contribution on the Request Tracker Wikia to look at the In-Reply-To header and merge it into the correct ticket, but has the following problems:

  1. They want to patch it directly against lib/RT/Interface/, which means the changes will be lost if you upgrade
  2. It contains an SQL injection attack vulnerability.

I cleaned it up and made it as an (based off RT 4.0.x) you can drop into lib/RT/Interface, you can find that here.

The RT authors suggest doing this as a mail plugin that modifies $SystemTicket, but that’s a project for another day.