Send a reply email back to sender if JIRA could not process it

Background

If a customer send an email to create issue or add a comment to an issue, sometimes JIRA failed to process the email, maybe due to the Permission or even the configuration itself. At the moment, JIRA did not inform the sender that the sent email failed to be added into JIRA.

Steps to reproduce

1. Create Incoming Mail Handler for Create a new issue or add a comment to an existing issue in JIRA
2. Do not the Create User option, and leave Default Assignee empty
3. Fill in the Forward Email field, so that any failed email will be notified to the Forward Email account
4. Send an email to the Mail Handler

Expected result

Both Forward Email and email sender are notified by JIRA

Actual result

Only Forward Email account is notified of the problem