It would be great if an agent could decide to respond to a ticket while changing the email address of the recipient user. It is currently possible to forward a ticket to another email address, but there is no record of it in the ticket's history. Thank you for your attention!
Allow responding to a different user - Feature Request - Deskpro Support
In addition: If the recipient sends a reply it should be visible in the ticket's message list too. Currently a reply is treated as a new ticket.