email bounces from google

[Rastus]

OK,
I have configured an e-mail account in ISPConfig3. It sends e-mail no problem but When I send to it from outside, e-mail grom my gmail account bounces with the following error:

Delivery to the following recipient failed permanently:

blog@domain.org

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 5.7.1 Unable to relay for blog@domain.org (state 14).

----- Original message -----

Received: by 10.100.208.14 with SMTP id f14mr3404815ang.205.1291589976211;
Sun, 05 Dec 2010 14:59:36 -0800 (PST)
Return-Path: <XXXXX@gmail.com>
Received: from [172.20.200.95] ([209.215.151.126])
by mx.google.com with ESMTPS id x31sm4696571ana.29.2010.12.05.14.59.34
(version=TLSv1/SSLv3 cipher=RC4-MD5);
Sun, 05 Dec 2010 14:59:35 -0800 (PST)
Subject: Re: testola
Mime-Version: 1.0 (Apple Message framework v1082)
Content-Type: text/plain; charset=us-ascii
From: XXXXX <XXXXXX@gmail.com>
X-Priority: 3 (Normal)
In-Reply-To: <9f59285a6b73c50b4711ed0b9525056e.squirrel@www.dom ain.com>
Date: Sun, 5 Dec 2010 17:59:20 -0500
Content-Transfer-Encoding: 7bit
Message-Id: <44307583-3EDB-4583-BD1C-1D12E038D670@gmail.com>
References: <9f59285a6b73c50b4711ed0b9525056e.squirrel@www.dom ain.com>
To: blog@domain.org
X-Mailer: Apple Mail (2.1082)

But when I send e-mail from my exchange server, it comes through with no problems.

I looked in the /var/log/mail.log file but it did not show any activity from gmail that I could see.

Suggestions?

[till]

Check the dns records for the domain "domain.org" if all MX records are pointing to the correct server.

[Rastus]

Till,
I checked the DNS and it was all OK BUT when I did an external port scan for the domain, it became evident that the firewall was porting all incoming e-mail traffic from our multiple IP addresses to a different server. Sending e-mail from that server to the ISPConfig server worked OK but outside e-mail servers could not find the ISPConfig Server.

Got it fixed.
Thanks