Sendmail: How does one blacklist annoying spammers?

jdow jdow at
Mon Jun 28 03:58:34 UTC 2010

Passing SPF means nothing. That simply means that the email was sent from
an address the sender's MX record says is OK for sending email through it.
So an SPF that allows the entire Internet to use the mail relay still
passes. If an email does NOT pass SPF it's probably a good guess that it
is spam, though.

----- Original Message ----- 
From: "Kevin J. Cummings" <cummings at>
To: <users at>
Sent: Sunday, 2010/June/27 19:14
Subject: Re: Sendmail: How does one blacklist annoying spammers?

> On 06/27/2010 10:04 PM, Ed Greshko wrote:
>> This one particular client doesn't use whitelists and they don't
>> experience any delays in delivery from those domains simply because they
>> have been populated in the DB and due to the frequency they connect
>> those records don't expire.
>> Oh, FWIW, there is no such thing as an "outbound MX host".  :-)
> I believe that's what SPF is supposed to solve.  Sites advertise in
> their DNS records which the "official" outgoing email servers are.  If
> you get email from that domain which *didn't* go through one of those
> servers, it must be SPAM (or a mis-configured source system, which I ran
> into once, and had to convince them that they violated their own rules).
> Not all systems support (or even recognize) SPF.  Some competing systems
> have even sprung up by Microsoft and Yahoo (the old "not invented here,
> therefore we must re-invent it" syndrome).
> -- 
> Kevin J. Cummings
> kjchome at
> cummings at
> cummings at
> Registered Linux User #1232 (
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