Group Email Alerts: set default to disabled

Hi, my client has a site that has some very active groups and members are complaining about the number of emails they are getting. Is there a way to set Group email alerts to OFF for all users until they activate them in their Notification Settings?

I DO NOT want to globally turn off email notifications. It is only the groups that are causing problems. It would be really nice to set default alert values for new users on an item-by-item basis.

Thanks!