#2 Apr 26, 2019 18:45
You have not provided any detail and are relying on other people here to ask questions, which is not a good idea
If you have your site to allow anonymous registrations not verified by email how do you verify ??
What settings do you have on User >settings > Registration ??
You could add a CAPTCH or Turin test that would stop a lot of bots but not humans spammers ??
There are many options but you haven't made any effort to say what you have tried. :(