The addition of an action code called "#merge" at the top of ANY email addressed or cc'd to the helpdesk and then the option being the Ticket ID. e.g. #merge  This action code would then merge the email message into the messages of the ticketID in the option. This ability gives you the power to have one on one conversations with vendors and other people outside of your organization that you do not necessarily want to be part of the ticket communications, but the information within those emails pertains to the ticket.
Update ticket via email using action codes - Feature Request - Deskpro Support
I also would like to #merge (or #ticket) because i've created a ticket manually, and then someone forwards me information to my private email. I want to forward that email to DeskPro so its part of the ticket history.