Hi,
some of our agents are forwarding inbound tickets to their own mail account or to the mail account of another agent. Then they close the ticket and work with their mail client, to communicate with the customer.
This is unwanted and have some behaviours, like customers will get an automated email, that their ticket is closed and so on. Is it possible, to disable the mail forwarding option for some groups?
No that’s not possible. Maybe with fiddling in the sources to hardly comment the part out but… well.
I think the main question would be why your agents prefer their local mail program over Zammad. This may solve the issue if the reason they don’t like to use it can be sorted out.
Ok, thank you.
To answer the main question - The mindset of some people in our company is “We’ve always done it this way.” It is hard to get them on the right way. 
Evil people could say that there’s legal actions that can be quite helpful to push people into directions. Any way, that’s hard to overcome I guess.
Ask them for ticket history when a new incident happens, last request etc. This helped to convince our more experienced colleagues to fully using a helpdesk.
Additionally consider hiding the button with some Css…?
Ah… 
That was simple.
[data-type=“emailForward”] {
visibility: hidden;
}
Thank you for the hint.
Keep in mind that this is only a visual cover.
Nerdy agents might find a workaround. Good workaround for the scenario though.