When sending out mails the mails ends as spam, error RCVD_ILLEGAL_IP

Our company sends out mails that customers subscribed for, some customers get the mails in their spam filters and when looking in to the mail I see RCVD_ILLEGAL_IP

What can I do to avoid our mails being seen as spam?
Return-Path: <Email address>
Received: from timmy3-clean.inbox.lv ([unknown])
         by brat23 (Cyrus v2.3-55) with LMTPA;
         Wed, 28 Apr 2010 16:39:13 +0300
Received: from localhost (ham1 [])
        by timmy3-clean.inbox.lv (Postfix) with ESMTP id DA5EEFE732
        for <Email address@inbox.lv>; Wed, 28 Apr 2010 16:39:13 +0300 (EEST)
X-Spam-Flag: YES
X-Spam-Score: 5.997
X-Spam-Status: Yes, score=5.997 tagged_above=2 required=5
        tests=[EXTRA_MPART_TYPE=1, HTML_MESSAGE=0.001, L_P0F_D9=-0.4,
        L_P0F_W=1.7, RAZOR2_CHECK=0.5, RCVD_ILLEGAL_IP=3.196]
Received: from kas3-ham.inbox.lv ([])
        by localhost (ham1.inbox.lv []) (spamfilter, port 25)
        with ESMTP id NmnAGHk3I-Ec for < Email address @inbox.lv>;
        Wed, 28 Apr 2010 16:39:12 +0300 (EEST)
Received: from exchfront.mercell.com (exchfront.mercell.com [])
        by timmy5-world.inbox.lv (Postfix) with ESMTP id 925BD6BB1C
        for < Email address @inbox.lv>; Wed, 28 Apr 2010 16:39:11 +0300 (EEST)
Received: from EXCHANGECLUSTER.mercell.com
 ([fe80:0000:0000:0000:021a:64ff:]) by exchfront.mercell.com
 ([]) with mapi; Wed, 28 Apr 2010 15:39:10 +0200
From: =?windows-1257?Q?M=E2rti=F2=F0_Ma=F2uks?= <Email address>
To: "Email address@inbox.lv" < Email address @inbox.lv>

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igaardAuthor Commented:
And since my ipaddress is 77.xxx.xxx.xxx it's not listed there, can you give me a hint to get further with this issue ?
The forwarding email server is 77.blah.blah.blah  but the originating address is [unknown].   Many (though not all) spam blockers will assume that unknown from  a regional TLD (like .lv) is invalid.
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igaardAuthor Commented:
Yes my mail server is 77.bla.bla.bla and you think that because it says Received: from timmy3-clean.inbox.lv ([unknown]) the originating address is unknown ?

What can I do ?
I'm not sure you can do anything except to correct whatever is causing your originating address to fail to resolve.  The problem is on the receiving end; the people running their clients are going to have to make an exception for your traffic.
You have always to make sure that your emails don't look like spam. Mail Security Applications analyse the mail usually as two parts:
1) SMTP Protocol
2) Contents.

Here are some hints on both of the two parts:

By passing the email processing during these two parts, each check will give a spam score, and by moving from one process to another the spam score might reach rate the considered as spam, so you might be doing some mistakes that makes your email looks like a spam, and with counting the spam score for these tinny things, you might be rated as spam.

From the first part, usually it will be checking for the early talker (boots) which will be running as script, and will send commands according to the script, and some mail security applications delay the response to make sure that the sender is responding and it's not an early talker boot.

It will check also for the nslookup on your domain, will check your domain and ip in the DNSRBL, then it will do a recursive nslookup on your IP to make sure that it returns your domain name.

Some mail security applications will check if the user you are trying to send to is legitimate and really exists.

Also will check the data command about the size, format, extensions of attachments, ...etc

Then it comes to the contents, where usually AV will scan any attachment, then the application will check any URL inside the mail body, and will check for scripts if any, will check the dictionary for any words that are used by spammers, also some check the symantec of the email.

Some other problems occur when your mail server is not standard, and it will be using different parameters like the data line is too long than the other mail servers, and this also cause your email to be rated as spam.

It's not only about your IP, Yes you have to send from clean IP, clean Domain, and must be pointing to each others, but also you have to make sure that your email doesn't look like a spam.

I hope I was able to provide you with some help,
igaardAuthor Commented:
Thanks to both of you, I just heard that it might be because I have enabled (or not disabled) IPv6 on my nic, so therefore I will disable IPv6 as a start, I'll let you know the result next week.

Thanks again for your time :o)

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You are welcome, I'm glad that it was solved after all.
igaardAuthor Commented:
Don't know if this issue is solved yet, I will know next week when the next subscriber mails will be delivered :o)
igaardAuthor Commented:
IPv6 was the reason....
Davids xxxCommented:
Can this portal send me cellphoone number to this woman - Cicek v. clarke???
Or how i can communicate with her?
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