This is a little off topic to SA but a good RBL setup is crucial to making SA successful. For those using Postfix, check the list archives for postscreen settings to use weighted RBLs which allows using of somewhat unreliable RBLs in combination with reliable ones which works very well to block ~98 of the junk using very light weight DNS checks.
Then you can allow whitelisting of trusted senders based on their SPF record which allows you to crank up the RBLs and their weights a little more aggressively in postscreen. https://github.com/stevejenkins/postwhite I have had to add comcast.net and other major ISPs that don't take care of their own outbound mail filtering which puts them on RBLs that I use in postscreen. These large ISPs can't be blocked without major collateral damage so I have to let these be handed by SA. Latest example is radware.com and 47.19.108.100 which has been up to some mischief the past 2 weeks so my senderscore.org score check blocked it in postscreen. http://multirbl.valli.org/lookup/47.19.108.100.html https://senderscore.org/lookup.php?lookup=47.19.108.100 Dave
