First of all, deeply thank you for this great project.

I would like to know how to control attaching files ability when sending a message to a user.

Much more, I would like to control sending message feature in general, for example;

A student can send a message only for his tutor.

A student can't attach a file in his message.

A tutor can send a message only for his course student's.

A tutor can attach a file, or can't, optional.

And some other options.

Thank you in advance.