I am facing this issue, I use the default postfix MTA in centos but the mail end up in user spam folder, but this does not seem to be a problem in Debian using exim4, both host have hostname and domain name configured, and relay mail through external smtp host. Both configuration and recieving email header are attached.

The different seems that Debian has this additional (envelope tag) and (from) tag other than some minor syntax differences.

Any help to resolve is appreciated.

The IP address and DNS is masked as follow:

1.2.3.4 = My IP address
smtp.host.com = external smtp host for my company
[email protected] = account at smtp host
centos.abc.com = Local centos server
debian.abc.com = Local debian server

Thanks.

Centos main.cf config with the following params configured

myhostname = centos.abc.com
mydomain = abc.com
myorigin = centos.abc.com
relayhost = smtp.host.com

Centos -> User receiving mail header

Return-Path: <[email protected]>
Received: from 1.2.3.4 [1.2.3.4] by smtp.host.com with SMTP;
   Thu, 27 Sep 2012 13:36:49 +0800
Received: by centos.abc.com (Postfix, from userid 0)
    id 1E0637B89; Fri, 28 Sep 2012 13:36:39 +0800 (SGT)
Return-Path: <[email protected]>
Received: from 1.2.3.4 [1.2.3.4] by smtp.host.com with SMTP;
   Thu, 27 Sep 2012 13:36:49 +0800
Received: by centos.abc.com (Postfix, from userid 0)
    id 1E0637B89; Fri, 28 Sep 2012 13:36:39 +0800 (SGT)
Date: Fri, 28 Sep 2012 13:36:39 +0800
To: [email protected]
Subject: Test mail from centos
User-Agent: Heirloom mailx 12.4 7/29/08
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Message-Id: <[email protected]>
From: [email protected] (root)
X-SmarterMail-TotalSpamWeight: 0
X-Antivirus: avast! (VPS 120926-1, 27/09/2012), Inbound message
X-Antivirus-Status: Clean

http://i.imgur.com/7WAYX.jpg

Debain exim4 config

....
# This is a Debian specific file

dc_eximconfig_configtype='smarthost'
dc_other_hostnames='debian.abc.com'
dc_local_interfaces='127.0.0.1 ; ::1'
dc_readhost='debian.abc.com'
dc_relay_domains='smtp.host.com'
dc_minimaldns='false'
dc_relay_nets='127.0.0.1'
dc_smarthost='smtp.host.com'
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname='true'
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'

debian -> User receiving mail header

Return-Path: <[email protected]>
Received: from 1.2.3.4 [1.2.3.4] by smtp.host.com with SMTP;
   Thu, 27 Sep 2012 15:02:53 +0800
Received: from root by debian.abc.com with local (Exim 4.72)
    (envelope-from <[email protected]>)
    id 1TH86d-00010v-G9
    for [email protected]; Thu, 27 Sep 2012 15:01:55 +0800
Return-Path: <[email protected]>
Received: from 1.2.3.4 [1.2.3.4] by smtp.host.com with SMTP;
   Thu, 27 Sep 2012 15:02:53 +0800
Received: from root by debian.abc.com with local (Exim 4.72)
    (envelope-from <[email protected]>)
    id 1TH86d-00010v-G9
    for [email protected]; Thu, 27 Sep 2012 15:01:55 +0800
Date: Thu, 27 Sep 2012 15:01:55 +0800
Message-Id: <[email protected]>
To: [email protected]
Subject: Test from debian
From: root <[email protected]>
X-SmarterMail-TotalSpamWeight: 0
X-Antivirus: avast! (VPS 120926-1, 27/09/2012), Inbound message
X-Antivirus-Status: Clean

http://imgur.com/nMsMA.jpg