BuddyPress.org

have they checked their junk mail / spam folders?
If your users aren’t happy about this, just wait until they start using it – lol it’s a crude work in miserable progress imho – the signup issueS are just the beginning. I would consider buddypress more of a hobby thing for those who want to spend long hours in multiple forums trying to hash out why everything does not work well together. You will find spam robots have no problem signing up and activated dozens of accounts daily. Once your users actually get activated they will have a great time trying to sort out real blog posts from spam, they may wish they never signed up in the first place – especially if they create their own group.