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I am pretty lost here, my server somehow got into a blacklist. And I don't know why and how to solve it. Please take a look at the link below.

CBL List - click here

Anyone knows what is going on here? I am not spamming mails, I am just hosting a forum.

I will provide any information needed, just reply.


EDIT: I have gotten this email.

This is the mail system at host localhost.localdomain.

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own text from the attached returned message.

              The mail system

<**>: host[] said: 550 5.7.1
: Helo command rejected: Host not found (in reply to RCPT TO command)

Final-Recipient: rfc822; * Action: failed Status: 5.7.1 Remote-MTA: dns; Diagnostic-Code: smtp; 550 5.7.1 : Helo command rejected: Host not found


My postfix settning:

myhostname = alias_maps
= hash:/etc/aliases alias_database = hash:/etc/aliases myorigin =
/etc/mailname mydestination =,,, localhost

(none):~# hostname -f
hostname: Unknown host
share|improve this question
up vote 3 down vote accepted

As the page states, the HELO is not why your server is listed.

IP Address is listed in the CBL. It appears to be infected with a spam sending trojan or proxy.

is why your server is listed. You'll need to figure out why it's being flagged as such and correct it.

Changing how your server identifies itself in the HELO is specific to the SMTP server that you're running. Can you give us a clue?


Ok, got it. You have a couple of problems based on your edit:

  1. CBL thinks you're spamming but offers no details on what exactly they're flagging you on.

  2. It looks like is rejecting your email because it can't validate the name your SMTP server is giving in the HELO command. You'll need to figure out where in Postfix to set the outgoing FQDN in the HELO and set it to something legitimate, such as If you send and receive email on the same server then it's easiest to set the FQDN to match your MX record and then you can create an SPF record that authorizes your MX to send email for your domain. None of these will guaranteee that your email will be accepted but will help.

share|improve this answer
@joeqwerty How do I find my MTA software? I am running a Debian server. And what is a cluse? thanks! – Muazam Jul 1 '11 at 2:17
LOL. Extra "s" there, it should have been clue. What email software (MTA = message transfer agent) are you running on the server? – joeqwerty Jul 1 '11 at 2:21
@joeqwerty I am using squirrelmail, is that a MTA? – Muazam Jul 1 '11 at 2:24
I don't believe it is. I've edited my question to make it more clear. What SMTP server (this is the MTA that I'm referring to) are you using to send emails from your server/domain? – joeqwerty Jul 1 '11 at 2:28
@joeqwerty I believe Postfix is. – Muazam Jul 1 '11 at 2:30

In the document to which you linked, was listed as a resource for people in your situation. Have you followed the steps outlined in that document? If so, what was the output of the commands (and the contents of the emails) you received as a result?

share|improve this answer
I sent a mail to helocheck\ and even I did not get any reply back. – Muazam Jul 1 '11 at 2:22

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