Hell @mahz10 !
Yes, using Content Compliance or Routing, you can restrict students from emailing groups at all.
I do it like this. A few images.


Here's the regex. We have made sure our automatic groups all follow the same syntax, and then added some variants which may be either automatic or manual. In Swedish the word "personal" means "staff", and "larare means "teachers", "elever" means "students".
^dl_.*.auto@edu.lomma.se|.*personal.*@edu.lomma.se|.*larare.*@edu.lomma.se|.*elever.*@edu.lomma.se|adv.admins@edu.lomma.se
This rule is set/enabled on the /Elever OU (students) and therefore doesn't affect staff.
(Actually it isn't. It's set in the / (root) and disabled for the /Staff OU.)
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https://wheretofind.me/@NoSubstitute