[Exim] Exim configuration question

I use exim on my home Linux box with good results, but with a rather
vanilla configuration file. I've set up a mail system for a local
school which now wants an expansion beyond the basics. The setup works
fine for standard inbound and outbound addressing to
teachername@??? type addressing, but the school would now
like to open controlled email ability for their students with addressing
such as studentname@??? .

The control they wish to effect is to allow email to students to only be
accepted if sent from other students or from teachers at the school,
i.e. accept mail to @student.schoolname.org only from @schoolname.org or
@student.schoolname.org. Likewise, email from students will only be
accepted for delivery if addressed to other students or to teachers.

What configuration changes do I need to make to set this up?

Billy