It is possible, I had a similar setup.
An email would get generated and sent to the Unit Head. To make it easier I used a link button that would start a new email that prefilled the To address, Subject, and a code of ~Approved~ or ~Denied~ in the body:
The links are this:
Link for Approved:
mailto:[=Email_KaseyaServer=]?subject=~ticid='[$TicketId$]'&body=~Approved~
Link for Denied:
mailto:[=Email_KaseyaServer=]?subject=~ticid='[$TicketId$]'&body=~Denied~
All the Unit head needs to do is click on one of the links and send the new email. Once Kaseya reads the new incoming email it will apply it to the existing ticket and then you can use an IF statement to determine the answer.
