Support services are offered from a pool of agents. If an email is sent by one person in the group, and that email bounces (temporary error, permanent error), the ticket should automatically reopen to appear on the dashboard.
Currently, the bounce is noted in the closed ticket, and no one sees it, particularly if the login is under an alias email (as is our case) so no one ever gets a personal email notification that the message failed. Delivery errors should appear directly in the ticket list or dashboard for the agent pool to see.
A few times this scenario has caused us problems - we send important information to clients already in our customer database, their inbox is full and we never find out about it until they are writing to us weeks later to ask about the very matter they were notified on. We verify they were sent the info, and there it is, the email bounced silently but the ticket stayed closed.