Sender and Recipient has same email address

Hello ALl, 

I have an problem on the email sending. We have application to send email to internet. But many emails are not delivered to the internet. When i see message tracking i can see Sender and Recipient has sender email address. (Same Email address) 

When i see message header i can see below one. 

X-CreatedBy: MessageSnapexcht-Begin injected headers
X-MessageSnapexcht-UTC-Time: 2014-02-25T10:25:01.514Z
X-MessageSnapexcht-Protocol-Id: 08D10028C25D0A26;2014-02-25T10:24:56.506Z;1
X-MessageSnapexcht-Source: Original
X-Sender: saaacq@contoso.com
X-Receiver: saaacq@contoso.com
X-EndOfInjectedXHeaders: MessageSnapexcht-End injected headers
Received: from exchSCC021035 (172.30.16.171) by exchCASHT01.contoso.ad
 (192.168.10.200) with Microsoft SMTP Server id 14.2.247.3; Tue, 25 Feb 2014
 15:55:01 +0530
MIME-Version: 1.0
From: saaacq <saaacq@contoso.com>
To: david_SA@yahoo.com
CC: saaacq@contoso.com
Date: Tue, 25 Feb 2014 15:55:01 +0530
Subject: Card Statement
Content-Type: multipart/mixed;
boundary="--boundary_92_20dafa4b-8bf0-4442-8784-a7727d0e1699"
Message-ID: <f01698c1-d884-4b81-bb9e-29638934c5ff@exchCASHT01.contoso.ad>
Return-Path: saaacq@contoso.com
X-MS-Exchange-Organization-OriginalArrivalTime: 25 Feb 2014 10:25:01.5147
 (UTC)
X-MS-Exchange-Forest-ArrivalHubServer: exchCASHT01.contoso.ad
X-MS-Exchange-Organization-OriginalClientIPAddress: 203.30.16.124
X-MS-Exchange-Organization-OriginalServerIPAddress: 192.168.10.215
X-MS-Exchange-Organization-AuthSource: exchcasht01.contoso.ad
X-MS-Exchange-Organization-AuthAs: Anonymous
X-MS-Exchange-Organization-MessageDirectionality: Incoming

Please advice me on this.