The email templates should be simplified and cleaned up.
Initial email: When the initial email is sent, a quick thanks and “your ticket was received” is good.
Comments The comment email should not have additional HTML added. Just enough to communicate the new comment (and the last one).
Simplicity is key here – keep all email correspondence as basic and as close to a ‘real’ email as possible. Think of the most popular, modern ticketing systems like Zendesk, HelpScout and Freshdesk.