> a massive number of the IPs that are in those abusive-IPs databases are VPN IPs and that would have a tremendous amount of splash damage
The IP blacklisting does not have to be permanent. It may be sufficient to blacklist IP network for ~30 days.
Blacklisted IP does not need to mean absolute block of new account creation. Bad IP should lower HamScore that account that uses this IP address has.
If HamScore of the account (due to other indicators) drops below blacklisting threshold - only then delete the account (and blacklist all indicators that participated in creating this spam account).
In this case blacklist is not absolute - the "splash damage" will be minimized.
Re: Invitation tree
> a massive number of the IPs that are in those abusive-IPs databases are VPN IPs and that would have a tremendous amount of splash damage
The IP blacklisting does not have to be permanent.
It may be sufficient to blacklist IP network for ~30 days.
Blacklisted IP does not need to mean absolute block of new account creation.
Bad IP should lower HamScore that account that uses this IP address has.
If HamScore of the account (due to other indicators) drops below blacklisting threshold - only then delete the account (and blacklist all indicators that participated in creating this spam account).
In this case blacklist is not absolute - the "splash damage" will be minimized.