Blocking with RBLs

Hi,

Is there a way to block with RBLs? I already have a really good and very trustworthy and accurate internal one that works extremely well and fast with my SMTP servers for years now. Is there a way to apply the same RBL to dovecot? Logs are really going crazy as they stopped with SMTP and started with IMAP for a while now since dovecot is wide open to these attacks. Anvil does not seem to do much here. I am looking for solutions other than fail2ban or anything similar to this.

Lefteris