How do I stop receiving excessive community emails from Apple?

You can either unsubscribe by a particular post by unselecting the "Bell" icon under the OP's question so you no longer receive any posts related to that thread.

Or if you chose to Follow a particular Community, you can go to that community and unselect the "Follow" button.

Or you can globally stop all messages you receive by going to your user icon in the upper right and choose "Edit Profile & Preference", then choose what type of communication you want.