I'd optimise that a bit: 1 - try not to use greylisting (it can be quite annoying some time when you are waiting for an important email) 2 - RBLs should be us

I'd optimise that a bit: 1 - try not to use greylisting (it can be quite annoying some time when you are waiting for an important email) 2 - RBLs should be used from within SpamAssassin in such a way that it raises the spam score, not directly in the MTA. There are loads of "good" addresses listed in RBLs due to carelessness and/or incompetence of the operators.