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Re: Mail from invalid users at my local dynamic DNS

2003-04-17 19:28:18
On Wednesday, Apr 16, 2003, at 23:21 Canada/Mountain, Professional Software Engineering wrote:
At 18:39 2003-04-16 -0600, LuKreme wrote:

Now, syth.serveftp.net is one of my dyndns domains and I know that there is no valid user on my machine named "Bill."

The mail no doubt is being injected directly at your server - if you check the Received headers, the first one (and, if you're reading mail ON that host, the ONLY one) will be when the message was passed from some host to yours.

From vmjc4mdu(_at_)sina(_dot_)com  Wed Apr 16 02:08:32 2003
Received: from localhost [127.0.0.1] by syth.serveftp.net
        with SpamAssassin (2.50 1.173-2003-02-20-exp);
        Wed, 16 Apr 2003 02:08:42 +391938
From: Bill(_at_)syth(_dot_)serveftp(_dot_)net, 
McLion(_at_)southgaylord(_dot_)com
To: kreme(_at_)cerebus(_dot_)kreme(_dot_)com
Subject: (Spam? 14.00) 1 million recipients spam free for only $129
Date: Wed, 16 Apr 03 15:50:39 \xd6\xd0\xb9\xfa\xb1\xea\xd7\xbc\xca\xb1\xbc\xe4
Message-Id: 
<20030416080831(_dot_)D8B6221FEDE(_at_)syth(_dot_)serveftp(_dot_)net>
X-Spam-Flag: YES
X-Spam-Status: Yes, hits=14.0 required=5.0
        tests=BAYES_90,BULK_EMAIL,CLICK_BELOW,DATE_IN_FUTURE_06_12,
              EXCUSE_1,EXCUSE_19,HEADER_8BITS,HTML_80_90,
              HTML_LINK_CLICK_HERE,INVALID_DATE,LIMITED_TIME_ONLY,
              REPLY_TO_EMPTY,SUBJ_FOR_ONLY,UNSUB_PAGE
        version=2.50
X-Spam-Level: **************
X-Spam-Checker-Version: SpamAssassin 2.50 1.173-2003-02-20-exp
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="----------=_3E9D0F8A.066BE8EE"
Status: RO
X-Status:
X-Keywords: Junk
X-UID: 838

What I find odd is that there is almost no info in the received header. Shouldn't postfix be keeping track of the IP address that connected? Anyway, that's not really the point. The question is, can I look at the "From: Bill(_at_)systh(_dot_)serveftp(_dot_)net" and have procmail somehow test if that usersname is valid:

:0
^ From:(.*\<)\/(_dot_)*(_at_)syth(_dot_)serveftp(_dot_)net
{
 LOCALUSER=$MATCH
 [ Some magic to check if localuser is valid]

 :0
 * [localuser is not valid]
 do stuff here...
}

I suppose I could check if the From: matched the From_ though, that might work.

Does it matter if I'm checking only LOCAL users or could i also check my actual remote mailserver?

Uh, please explain. Sounds like your email may arrive on a host and you're fetchmailing it? Where is procmail running? Where are the SMTP connections coming in?

Mailserver is southgaylord.com/kreme.com and I get mail down via fetchmail. The syth.serveftp.net is my home machine using dyndns and has accounts for me, my family, and some friends. I do get SOME mail directly to the dyndns domain, but very very little.

--
I wrote this song two hours before we met. I didn't know your name, or what you looked like yet....


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