Hi @EdwardThome ...
You cannot control and/or configure notifications that your students receive via their own communication methods, but they can control that on their own. In fact, all users (no matter if you are a student or an instructor) are able to control their own notification settings both at the entire user level and per course. Notifications can be sent out immediately, daily, weekly, or not at all. Here are the two Guides that you could give your students:
Again, all users are able to configure their own notification settings based on their personal preferences. So, you won't be able to configure anything as a "default" for your students.
I hope this will be helpful to you. Sing out if you have any questions about this...thanks!