Here’s how to reduce or eliminate notifications from groups (video below)
In your email, scroll down in the left column until you see the list of groups you are a member of.
Choose a group. Then in the next column, just below the Group name, click the three dots …., and then click Settings
This will open a new pane on the right edge where you can choose when or if you get notifications from this group.
Related post: How to schedule with the group calendar
Related post: How to remove yourself from an Office 365 group