MyBB Community Forums

There are up to 50,000 posts in my forums, and 1,000 unknown users coming to spam my account. How do I fix this? Plus how do I remove all posts and accounts in one go?

IP Ban the members then add this plugin https://mods.mybb.com/view/no-proxy-please (1.6 plugin btw) or get lots of VPN IP's and block them. Also credit to
ranjani for the link. I go on a forum for v3rmillion.net and they block a good range of VPN's but people still multi-acc (make new accs) so you can't block them all but block common ones.

you need some better security questions and use post flood checking till they are gone

security questions
https://community.mybb.com/thread-180635.html

post flood checking
https://community.mybb.com/thread-62504.html

Use the purge spammer option to ban delete all the post . I would not suggest you ban proxy or VPN connections because it will most likely block legitimate users.

There are a few things you can do to limit the amount of spam on your forums.

1. Allow MyBB to Query Usernames, Emails, and IP Addresses against StopForumSpam. There are options in the admin control panel to enable this.
   
2. Use the 'purge spammer' feature to your advantage and use 'ban' rather than 'delete'. By doing that (someone correct me if I'm wrong) MyBB also issues an IP Address ban.
   
3. Enable nocaptcha recaptcha rather than the default captcha. It's harder for bots to bypass this. You will however need to use https://www.google.com/recaptcha/admin to get an api-key for your site.
   
4. If it's a lot of bots registering then automatically registering then you could use a service like WebDeflect and enable the browser check to prevent the bots from being able to register. Most bots won't be able to bypass the browser check so it'll reduce the amount of spammers.
   
5. Add a longer post flood limit. This will at least make spam a little more manageable.
   
6. You could install this plugin and require a captcha to post anything. If I were you I would setup a "new users" and "approved users" usergroup. Use the group promotion system to automatically promote "new users" to the "approved users" after five posts.
   
7. For my forum I choose to require approval of your first few posts by site staff. Follow the steps listed here to do so.
   
8. You could add different security questions to make bots lives harder.
   
9. Keep in mind that most of the above options will not stop a targeted attack where someone is spamming manual but it'll cut off bots spamming and make your spam flow easier to manage.
   

Hopefully this helps you a bit and let us know if you have further questions