Currently if one has subscribed to the "Satellite sync errata" you get an email for all repositories even there are no new synced packages for the repository. This ends up being quite a few emails every time your sync plan(s) are executed.
These emails should be made optional or removed, or perhaps when a sync plan has finished and there are no new updates in any repo there could be one email sent just to notify the user that there were no new updates but mostly to ensure the user that the notifications are working.