Maintain email chains (a.k.a email threads) in Jira

Email Chains are important to keep track of email conversations and properly represent them in Jira as issues and its comments.

By default the email chain is maintained via the issue key appearing in the subject. If this is not possible, we can only rely on message ids.

Message IDs are unique identifiers set in the header part of the emails by the email server that dispatches them.

The following is a typical situation.

Anne sends email to Bill and Corp, where Corp is the mail account from which Jira processes the emails. The email does not contain any reference to an issue.
The issue is created in Jira by our Next Gen Mail Handler
Bill receives the email and uses the Reply All function of his mailer app to send a reply to Anne and implicitly to Corp as well, since Corp was on the original email.
The reply email reaches Anne and Jira, but as it lacks any valid issue ID, normally a new issue is created. The preferred solution was to save Bill’s response as a comment in the issue created from Anne’s email.

This is a problem and causes confusion in many cases. Follow the below descriptions for a solution.

Instructions

If you are on Server or Data Center, please find the solution to this problem here: Maintain Email Chains (Email Threads) in Jira