Hi, We have recently installed plesk for linux 9.3, the OS is CentOS and the MTA is qmail. Sometimes when we send a mail for example to firstname.lastname@example.org we recieve a Failure notice with the mail that we send but it says that it could not be send to some users, (notice that we only sent the mail to email@example.com). It's like drigdon@sd-5266 is sending mails but we didn't have any user and any domain like sd-5266. Here is an example (the mails and ip's are not the real ones): Hi. This is the qmail-send program at plesk.somebusiness.com. I'm afraid I wasn't able to deliver your message to the following addresses. This is a permanent error; I've given up. Sorry it didn't work out. <CENSORED@test.es>: Connected to 188.8.131.52 but sender was rejected. Remote host said: 553 #5.1.8 Domain of sender address <drigdon@sd-5266> does not exist <CENSORED@csbs.jcyl.es>: Sorry, I couldn't find any host named csbs.jcyl.es. (#5.1.2) <CENSORED@telefonicaa.net>: Connected to 184.108.40.206 but sender was rejected. Remote host said: 550 5.1.0 <drigdon@sd-5266> sender rejected --- Below this line is a copy of the message. Return-Path: <CENSORED@CENSORED.COM> Received: (qmail 20094 invoked from network); 9 Feb 2010 15:48:20 +0100 Received: from 99.net-99-99-9.staticip.net (HELO test) (220.127.116.11) by 10.51.0.7 with SMTP; 9 Feb 2010 15:48:20 +0100 Message-ID: <007201caa995$bbffdf90$290101c0@test> From: =?iso-8=ED_V== <CENSORED@CENSORED.COM> To: firstname.lastname@example.org Subject: CENSORED Date: Tue, 9 Feb 2010 15:39:50 +0100 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_006F_01CAA99E.1DA2DCE0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1933 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1933 We didn't find anything in logs and don't know what's happening. Thanks in advance.