Some developers may work on their own private branches and constantly push changes to them. So commit notification emails are just spam to them and nothing else.

If users can filter notification emails based on branches, it would be great; the notification emails will more relevant and will help avoid spam.

This can be as easy as adding regex for notification emails, just like it is done for preventing deletion of branches or rebases.

Something simple like:
notification emails only for:
master
release-branch-*

will work great.