[Novalug] postfix - greylist before or after RBLs?

[Gopher]

I'm trying to tune my Postfix config and I've run into a small 
conundrum, which should fire first: RBLs or greylisting? I'd like to 
have as much non-network related checks fire before having to open 
connections from my box.  This seems like a reasonable approach as it 
should keep the overhead for running Postfix (cpu, memory, bandwidth) as 
minimal as possible. (And no, my box/network is not stressed for 
cpu/memory/bandwidth, I'm just trying to not waste resources if I don't 
have to.)

Greylisting works on the assumption that the sending client is a 
non-spambot if they come back later as instructed. Based upon this 
assumption, most/all of the spambot generated spam (which I believe is a 
very large volume of the spam on the net) should never get past this 
point.  If the spam does get past my greylisted then the RBLs I have 
configured should deal with it.

Agree/Disagree?

thx
Gopher.

-- 
gopher at 3wa.org
"Evil is, as humans do" - The Misfits