I am trying to make online forms for my company (forms like requistion e.t.c.). What i have in my mind is that the user log into the website complete the form and submit, on submit an email should be generated to the head of the concerned department. So far this phase is ok, but what i am keen to know is that when the Head of depart reply to that email received, it should have a field or area where remarks can be added by him.

Hence the head shouldn't bother going to the website to reply rather he/she should be able to do that via email generated.

Please tell me how this can be achieved ?