I was trialling Service Desk and had following requirement:
* Internal user sends email to helpdesk
* Ticket is created
* Agent looks at it and sees, ok its a ticket for our third party supplier.
* Agent forwards the ticket to the external supplier email address
* External supplier email system comes back with a ticket number
* Agent replies and goes back and forth with external supplier
* When issue is solved with external supplier comment is given to internal customer
* If all good agent closes internal ticket.
I cannot really find a way how to deal with this using Jira service desk as there seems to be no forward ticket to email option?