nanog mailing list archives

Re: spamassassin


From: Private Sender <nobody () snovc com>
Date: Tue, 18 Feb 2014 20:01:58 -0800


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On 2/18/2014 7:10 PM, Suresh Ramasubramanian wrote:
DKIM serves to authenticate the source of the message. So this is a stock
tip spam sent through an email service provider called icontact, and the
dkim signature declares that.  Just that and nothing more.

Says nothing at all about the email's reputation - whether it is spam or
not.

--srs

On Tuesday, February 18, 2014, Randy Bush <randy () psg com> wrote:

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On 2/18/2014 7:10 PM, Suresh Ramasubramanian wrote:
DKIM serves to authenticate the source of the message. So this is a stock
tip spam sent through an email service provider called icontact, and the
dkim signature declares that.  Just that and nothing more.

Says nothing at all about the email's reputation - whether it is spam or
not.

--srs

On Tuesday, February 18, 2014, Randy Bush <randy () psg com> wrote:


Yeah, it just validates the domain that the email came from.

But,

"X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on ran.psg.com
X-Spam-Level:
X-Spam-Status: No, score=0.8 required=5.0
tests=BAYES_50,HTML_MESSAGE,MIME_QP_LONG_LINE,*T_DKIM_INVALID*
autolearn=ham version=3.3.2"

Spamassassin knows the dkim signature is invalid, so there must be a dns
query that occurs at this point in the message processing.

If that is the case, there must be someway to configure to reject if the
dkim signature is invalid.

"X-Spam-Status: No, score=0.8 required=5.0"

Spamassassin isn't going to block anything until it registers a score of
5. So, just having a dkim signature (even though invalid) is possibly
lowering the score. Maybe you could tweak the settings to pick-off spam
at a lower score. But, setting your levels down to 0.8 would probably
block legitimate email.

You could always block their ip in the helo_access (or iptables) of your
postfix server (I'm assuming that's what you are using). But that's only
going to be a temporary fix.

You could also add a rbl query to your mail server config to spamhaus.
That could always help.
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