I know that the technology of direct answer for email to the forum is complicated. I still didn't see solutions for this. To not to be the old technology of Majordomo and similar that is not worth to think now.
The problem is that there are people that still have a lot of difficulty of understanding that, when doing a simple reply of the message arrival of the Forum for our inbox, we are not answering to the Forum. We are answering to the person that wrote. The people think that it works as in a discussion lists. As says the Philosophy of Moodle: we have to think as the student.
But, I see an alternative solution that has been used a lot by other systems. A simple solution that it could be done in /mod/forum/lib.php:
Instead of Moodle to send in "From" of the header of the message the author's of the message email, could appear or the teacher's email, or simply an email adress of the type "noreply etc.". Or the Forum title. Various possibilities.
I know that is a grotesque solution! But the one what to do if we don't have an elegant solution? That solution is used by several forum systems, as the phpBB, for instance.
I would like to do that alteration urgently in my Moodle. Because this is bringing problems. I would like to move directly in the file, to do a hack. But I would have to study that change. That would demand time that I don't have.
Maybe somebody that has already studied better this program (or problem) can help me.
The one that I have to do so that appears in "From" from who receives an email message from of a Moodle Fórum, something as:
"No reply this message. Use the link below to answer."
from Sao Paulo/Brasil