Majority of Users Not Activating

Hello

I run a social networking website using Buddypress. I have no coding experience. I have a separate email for new user notifications and was pleased to have over 60,000 new user notifications, but was then shocked to discover on dashboard, users over 310,000 pending users. I tried joining under a different email to my admin ones but did not get an activation email. I have the option to manually activate users, but there are too many. How can I get all users to be automatically approved and not just some?

Thanks

Sharon