SPAM with my Plesk Server

[julienacs]

Hello,
I have a concern of spam on my plesk server
Indeed, my server sends many spam using a mail part of my domain.
Here is an example of spam that is in the queue for my server

Received: from myservername (localhost.localdomain [127.0.0.1])
	by myservername (Postfix) with ESMTP id 0BA061242003;
	Mon, 27 May 2013 15:05:43 +0000 (UTC)
Received: from mydomain.com (unknown [37.215.26.173])
	by myservername (Postfix) with ESMTP;
	Mon, 27 May 2013 15:05:42 +0000 (UTC)
Message-ID: <[email protected]>
Date: Mon, 27 May 2013 16:05:46 +0100
From: "[email protected]" <[email protected]>
MIME-Version: 1.0
To: <[email protected]>
Subject: Got erection disorder? Our up-to-date supplements are highly recommended!
Content-Type: text/html;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

the line from mydomain.com (unknown [37.215.26.173]) the IP is not one of my server.
It fills my queue and my server crashes.

However, I have the required authentication to use my smtp server.
to test, I disabled the email address that sent the spam, but a few days later another address of my domain was used.

how can I permanently solve the problem because the reputation of my server is the lowest ...

thx in advance

 

[IgorG]

Check it http://kb.parallels.com/114845

 

[RobertvS]

In KB 114845 sendmail.postfix is used, but I only have sendmail in my /usr/sbin. Is this the same and shoud I replace sendmail.postfix with sendmail?

 

[IgorG]

In KB 114845 sendmail.postfix is used, but I only have sendmail in my /usr/sbin. Is this the same and shoud I replace sendmail.postfix with sendmail?

Are you sure that you have Postfix MTA but not Qmail? Have you read Note in article?

 

[RobertvS]

You are right. In KB 1711 sendmail is in /var/qmail/bin, but I haven't. Sendmail is in /usr/sbin. Can I replace the /var/qmail/bin / with /usr/sbin/ ?

Edit:
FYI I have Plesk Panel 11.0.9 and see in "Services management"-> "Pelsk milter (Postfix)" and "SMTP Server (Postfix)". So it looks that I'm running Postfix, am I right?

 

[NikosA]

In KB 114845 sendmail.postfix is used, but I only have sendmail in my /usr/sbin. Is this the same and shoud I replace sendmail.postfix with sendmail?

I have exactly the same situation on 2 Servers running Plesk 11.5 with Postfix (Ubuntu 10.04 & 12.04). The folder /usr/sbin has no sendmail.postfix file. Which file should be used instead?

Thank you in advance!