Below is a my message to the postfix users list, with a response from Craig
/ Australia. I plan to set Postfix up on FreeBSD 3.4-Release and put up a
little website about how to configure it as a anti-spam front-end to Imail,
when I'm sure it's running ok, within the next two weeks.
www.FreeBSD.org or www.FreeBSDmall.com (to buy The Complete FreeBSD book +
cdrom set)
Or, for free, the bootable .iso cdrom image (fed to something like Adaptec
CD Creator) is available from:
ftp.freebsd.org - I couldn't get it to repspond, but there are dozens of
mirros world-wide, such as:
ftp://ftp.de.freeBSD.org/pub/FreeBSD/releases/i386/ISO-IMAGES/3.4-install.is
o
I mention the latter because I grabbed my .iso images there at 1.1
megabits/sec, once for 3.4 and once for 4.0 RC2 ! The 3.4 .iso image is
about 630 megabytes.
www.PostFix.org and http://www.porcupine.org/postfix-mirror/start.html
The software cost is open source and, of course, free. For those of you
that prefer "brand name" open source OS's, vbg, I don't think anything I'll
do on FreeBSD will be different on Linux.
The hardware should probably be a 100 to 200 MHz Pentium minimum with 32
megs, maybe 64.
The FreeBSD/postfix box could also serve as the outgoing mail server
instead of Imail, reserving Imail for POP3, IMAP, web messaging, and list
services. To do this, the postfix box would be setup as Imail's "forward
all mail to" gateway.
Postfix, like Imail, does header filtering with Regular Expressions, but
from what I've seen in a quick overfly, doesn't do content (body) or
attachment filtering, but there are, as is typical in open sourece, lotsa
"hacks" for postfix to do almost anything.
=======================================================================
Date: Mon, 28 Feb 2000 13:14:15 +1100
From: Craig xxxxxxxxxxxxxxxxxxxxxxxxxx
To: Len Conrad <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED]
Subject: Re: PF only as scrubbing-relay?
:
:
:
:
:
User-Agent: Mutt/1.1.4i
:::
X-RCPT-TO: <[EMAIL PROTECTED]>
:
:
> I represent a group of Imail users who are looking to build a
> spam-defense front-end for their Imail servers which have fairly
> effective header and body filtering rules, but no reverse or MX
> lookups and no RBL lookups. Postfix's reputation encourages us to
> look at PF for this "appliance" role. I'd appreciate thumbs up/down
> on the feasability of following big picture and general direction to
> take to put it all together, please:
postfix would do a good job of this.
setting it up would be fairly easy - it's all quite straight-forward,
nothing unusual or difficult in the setup.
> The Postfix appliance would have these tasks:
>
> 1. Accept all mail for the allowed domains. (there would be no mail
> domains or local accounts on the PF machine). The PF machine would be the
> primary MX record for the protected mail hosts.
add the domains to postfix's $relay_domains. don't add them to
$my_destination or to $virtual_maps.
> 2. Reject all incoming mail for unknown domains.
automatic. or, more precisely, postfix will only relay to domains listed
in $relay_domains or from IP addresses listed in $mynetworks (i.e. local
ip addresses - your workstations)
> 3. For accepted msgs, apply the various UCE defenses, RBL, reverse
> lookup, and header-filtering rules, dropping and logging all rejects.
fairly easy to set up. postfix's anti-spam capabilities are one of the
main reasons i use it....it's great that it is fast and secure too, but
the deciding factor for me is that it has the best anti-spam features
that i've seen in any MTA.
> 4. Relay all accepted traffic to the known domains' ip addresses,
> using a hosts file rather than DNS, since the each known domain would
> only have its primary MX record pointing at the Postfix machine.
best done using a transport map. e.g.
domain1.com smtp:[ip.address.or.hostname]
domain2.com smtp:[ip.address.or.hostname]
domain3.com smtp:[ip.address.or.hostname]
.
.
.
when mail for domain1.com (or domain2 or domain3) arrives and passes the
$relay_domains check, postfix forwards it using the specified transport
(smtp) to the specified next-hop address.
craig
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