Email delivery failure

Hi,

I am having a strange issue. When I am sending an email to someone whose email address exists, after I hit  the send button I get an automated email saying:

"This is an automatically generated Delivery Status Notification. Delivery to the following recipients failed."

But the person still receives the email. I don't know what's the issue ad was wondering if you could help me out. This problem is rather annoying and  keeps me guessing if the person on the other end actually received my email or there was an actual mail delivery failure. For convenience, this is the Message Source:

"x-store-info:D6taffyBScEUZsL+ZXbbDoZx0yi5SZys1eYEToP0rSM/bCVLqYrYYCvSWjNvmELua9FHP+r2G/qC3lXTKg5U/5j7HMg9GTuqcV6lHbw5fgUocJxvj1i8PLlMqIGjqOxM80Nep68NNIw=
Authentication-Results: hotmail.com; spf=none smtp.helo=blu0-omc3-s33.blu0.hotmail.com; dkim=none header.d=mail.hotmail.com; x-hmca=none header.id=*** Email address is removed for privacy ***
X-SID-PRA: *** Email address is removed for privacy ***
X-AUTH-Result: NONE
X-SID-Result: NONE
X-Message-Delivery: Vj0xLjE7RD0wO0dEPTA7U0NMPTk7bD0x
X-Message-Info: AuEzbeVr9u5fkDpn2vR5iCu5wb6HBeY4iruBjnutBzpStnUabbM/X3OHG1tkHI7a3kMiU15mwZkdItk0fkPUd26iJME4hbgAI/g6pso0Zyh7O0XVOq5g8hCf8Efy9J5lqUsPh7BGuOg=
Received: from blu0-omc3-s33.blu0.hotmail.com ([65.55.116.108]) by SNT0-MC2-F38.Snt0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4900);
	 Fri, 16 Aug 2013 06:49:01 -0700
From: *** Email address is removed for privacy ***
To: *** Email address is removed for privacy ***
Date: Fri, 16 Aug 2013 06:49:01 -0700
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
	boundary="9B095B5ADSN=_01CE8E5B9779F666000B39D7blu0?omc3?s33.bl"
X-DSNContext: 7ce717b1 - 1196 - 00000002 - 00000000
Message-ID: <*** Email address is removed for privacy ***>
Subject: Delivery Status Notification (Failure)
Return-Path: <>
X-OriginalArrivalTime: 16 Aug 2013 13:49:01.0508 (UTC) FILETIME=[5D310840:01CE9A87]

This is a MIME-formatted message.  
Portions of this message may be unreadable without a MIME-capable mail program.

--9B095B5ADSN=_01CE8E5B9779F666000B39D7blu0?omc3?s33.bl
Content-Type: text/plain; charset=unicode-1-1-utf-7

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

       *** Email address is removed for privacy ***




--9B095B5ADSN=_01CE8E5B9779F666000B39D7blu0?omc3?s33.bl
Content-Type: message/delivery-status

Reporting-MTA: dns;blu0-omc3-s33.blu0.hotmail.com
Received-From-MTA: dns;BLU173-W42
Arrival-Date: Fri, 16 Aug 2013 06:48:58 -0700

Final-Recipient: rfc822;*** Email address is removed for privacy ***
Action: failed
Status: 5.5.0
Diagnostic-Code: smtp;550 Blocked

--9B095B5ADSN=_01CE8E5B9779F666000B39D7blu0?omc3?s33.bl
Content-Type: message/rfc822"