[CentOS] Re: Postfix Questions

Scott Silva ssilva at sgvwater.com
Tue Sep 18 20:04:08 UTC 2007

John Hinton spake the following on 9/18/2007 12:00 PM:
> 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.
You should be able to exempt your outgoing mail from the milters.

> 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.

If your client is on a dynamic IP, then since you are hosting them that would 
put you on dynamic IP's. So if you are hosting them, and they are on dynamic 
IP, you are responsible if they end up on a blacklist, since you have ultimate 
control of the IP space you host.

  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>


MailScanner is like deodorant...
You hope everybody uses it, and
you notice quickly if they don't!!!!

More information about the CentOS mailing list