I'm not sure how or why, but I all of a sudden stopped receiving emails notifications upon new user registration.
CB doesn't suddenly stop working, something you've done or host has changed resulted in this.
I did erase the original SuperAdmin and created another superadmin (actually two now). Under settings - moderation I have Super Administrator selected in the Moderator Group and "Send moderators Email" is set to yes.
Please edit your user and ensure they're configured to receive moderator emails. Once done ensure you've configured CB to send moderator emails on the Moderation tab. Why did you delete the default admin? This is ill-advised on any install.
I'm still using CB 1.4
Please upgrade to CB 1.7.