Ability to add comment via email as customer when not a participant

Problem Definition

With ability to add participants added, only the reporter and participant can add comments to a Service Desk thread. If a service desk customer account has received the service desk issue's email thread as a forward, and tries to reply as a comment, it just creates a brand-new ticket.

Suggested Solution

Service desk should recognize the issue ID as JIRA does and add the comment to the ticket.