Edit Ticket -> Add Email

I am trying to add an email address under the “Email Addresses” tab in the ticket detail view.

I get the following options:

1. Can Receive User Notification Emails
2. Can Receive Agent Notification Emails
3. User Can Edit
4. User Can Delete

I created the user in advance to make sure they were present. I assigned the role “Support Supervisor” (None of the other roles seem to be able to actually edit a ticket.)

I added a reply to the ticket, and the user got an email (that’s great!) with a button linking to the ticket. However, when the user clicks the ticket, he gets taken to the ticket backend without being able to actually edit the ticket.
Looking at the Email Adresses tab again, it looks like the user is given the roles Agent and User, none of which are actually allowed to edit a ticket.
See attached images.
https://www.dropbox.com/s/nqc0grbtjd98fn9/Edit.jpg?dl=0
https://www.dropbox.com/s/swd12wd5v9dwjpn/User%20roles.jpg?dl=0
https://www.dropbox.com/s/z7y4699jz9iuuk8/Actual%20role.jpg?dl=0