Re: Good Resource for additional Spam Blocking

7 msg	Invalid Sender Address syntax
2 msg	high availability
2 msg	BFD (Brute Force Detection) & Postfix
5 msg	relay domain and forwarding
2 msg	dk-milter - emal size issues
5 msg	Mail sent from local machine shows undisclosed-...
16 msg	Sorting incoming mails according to rules
5 msg	Correct use of smtpd_tls_security_level
1 msg	graph queue sizes
6 msg	large deferred queue ('too many connections')
3 msg	To see IP's
5 msg	How Can I Block certain IP's Within Range of my...
8 msg	Question about adding a special header to emails
3 msg	rcpt count mismatch and corrupt queue file ?
2 msg	too many connections
11 msg	Whitelist broken email servers?
4 msg	Write failed in network_biopair_interop with er...
2 msg	Pattern-matching in HELO
3 msg	header_checks du jour

Good Resource for additional Spam Blocking
\ Joey (15 Jun 2007)
. \ Joey (15 Jun 2007)
. \ Victor Duchovni (15 Jun 2007)

Subject:	Re: Good Resource for additional Spam Blocking
Group:	Postfix-users
From:	Victor Duchovni
Date:	15 Jun 2007

On Thu, Jun 14, 2007 at 08:07:13PM -0400, Joey wrote:

>
>
> We are not a BIG isp, so this is a good number from my perspective. To give
> you an idea in April 07 we blocked the following amounts of spam with RBL's
> on 1 server:
>
> blocked using zen.spamhaus.org (total: 219101)
> blocked using bl.spamcop.net (total: 12087)
> blocked using dul.dnsbl.sorbs.net (total: 11488)

These three appear to be doing useful work for you with very few FPs.

> blocked using dnsbl.njabl.org (total: 2379)
> blocked using dsn.rfc-ignorant.org (total: 1181)
> blocked using list.dsbl.org (total: 1065)
> blocked using spamsources.fabel.dk (total: 403)
> blocked using dnsbl.ahbl.org (total: 265)

I would ditch these, as the value gained is negligible (<1%), and at
least RFCI is not widely considered safe for use with blocking (major
ISPs or Country TLDs end up listed for long periods of time).

> On the flip side if anyone has additional ideas, please let me know since
> you can NEVER block enough spam!

You can block too much non-spam, or impose unnecessary latency doing
lookups that rarely do anything useful, but can really slow down your
system if the service in question is busy or down. RBLs are not the
whole story, some content filtering is also required (SA, DSPAM, choose
your poison).

--
Viktor.

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