[CentOS] Postfix Questions

Tue Sep 18 19:00:01 UTC 2007
John Hinton <webmaster at ew3d.com>

I've been running sendmail since the beginning of my online time.

1. Did I see that postfix can run sendmail milters?
2. If so, did I read that postfix can run these separately for inbound 
vs. outbound?
3. Can it run like a rbl blacklist on inbound and not outbound?
4. If the above is true, does this require separate configurations of 
postfix or is it already set to allow this out of the box?

My reasoning... I've added a few milters which has drastically cut spam 
due to the extra time spent at the smtp level. For instance, running 
spamassassin takes a couple or few seconds. This bit of delay does in 
fact seem to stop many of the slamming spambots sort of like the design 
of milter-greylist. Except, I don't have to send a temp fail. So, this 
is a good thing. The negative is it also takes longer for my users to 
send mail as it is processed the same way during outgoing.

Also, we run the SpamHaus blacklist. This works pretty good for inbound, 
but from time to time one of our hosting clients winds up on the 
blocklist because they are on a dynamic IP and someone else has recently 
used it for spamming. One could argue that my client should then go 
remove their IP from the blacklist to better insure their email actually 
makes it through any other level of spam filtering on other ISPs. But, 
that's a rosey concept! So, I would prefer to do it at the smtp level 
inbound so I can actually reject that mail while not having the 
embarrassing blocking going on with our users. Yes, this might sound 
like a double standard, but we do not provide connection service so only 
very rarely (never so far) does any virus actually send spam through our 
systems from client applications and I do actually monitor email all the 
time and stop any spamming immediately.

Thanks for any input.

John Hinton <who still keeps eyeballing postfix but is so comfortable 
with sendmail>