You can control email notifications for comments on your storyboards on a user by user basis. If you're an admin, you can toggle email notifications for all of your team too.
By default, all team members for a given storyboard will get email notifications for new comments left by other users or guests.
To change preferences for you and your team, just click the comments link in the header of your storyboard, then the settings icon in the top right hand corner. There's a link which appears in all the comment email notifications which will take you here too.
It's worth noting that notification settings apply to all versions of the storyboard.