DNSBL and SURBL questions

[Cadmailer]

Hello,

I have a few questions:

1) Proxmox mentions SURBL on the website but where do you set this up on admin page? Does Proxmox use the DNSBL to check the message body of emails?

2) What DNSBL services are supported by Proxmox?

3) Does Proxmox has its own spam signatures or does it rely solely on DNSBLs?

Thanks!