cannot able to send and receive emails from our company to other comany

Dear All,

recently we have installed Exchange anti-spam in our exchange 2007 server. after the problem starts, we cannot able to send and receive emails from our company to other comany           (for yahoo or hotmail its working fine).

we dont want to uninstall the anti-spam as we are getting lots of spam mails.

when ever we are trying to send an email its giving the below message:-


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Diagnostic information for administrators:

Generating server: exchange2007.aayanleasing.loc

kais@alesayi-motors.com
amc02-mail.alesayi-motors.com #550 No RDNS entry for 212.116.216.98 ##

Original message headers:

Received: from exchange2007.aayanleasing.loc ([192.168.1.10]) by
 exchange2007.aayanleasing.loc ([192.168.1.10]) with mapi; Mon, 1 Mar 2010
 12:24:14 +0300
From: Raed Ahmed Alkhayat <ralkhayat@aayanleasing.com>
To: "kais@alesayi-motors.com" <kais@alesayi-motors.com>
Date: Mon, 1 Mar 2010 12:24:13 +0300
Subject: Quotation Request
Thread-Topic: Quotation Request
Thread-Index: Acq5IIqkt9j/fP6BRmqL8bur4gY8tgAAFcsQ
Message-ID: <514B05B0B698B04EB28F8909BE36B39F1B6350FB09@exchange2007.aayanleasing.loc>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach: yes
X-MS-TNEF-Correlator:
acceptlanguage: en-US
Content-Type: multipart/related;
            boundary="_004_514B05B0B698B04EB28F8909BE36B39F1B6350FB09exchange2007a_";
            type="multipart/alternative"
MIME-Version: 1.0