Just a little heads up,
I just looked that the docs on MyBB's forum and someone pointed out that you can block entire domains from signing up.
So if all those spammers are using mail.ru, you could block mail.ru for some time and that would stop spammers from signing up.
Admin CP -> Configuration -> Banning -> Disallowed Email Addresses
then type *@mail.ru or whatever domain it happens to be.
You wouldn't do it for hotmail or gmail, but works great for those Russians mailboxes.
Source: https://community.mybb.com/thread-88897.html
I just looked that the docs on MyBB's forum and someone pointed out that you can block entire domains from signing up.
So if all those spammers are using mail.ru, you could block mail.ru for some time and that would stop spammers from signing up.
Admin CP -> Configuration -> Banning -> Disallowed Email Addresses
then type *@mail.ru or whatever domain it happens to be.
You wouldn't do it for hotmail or gmail, but works great for those Russians mailboxes.
Source: https://community.mybb.com/thread-88897.html