Problem sending (receiving?) email

Please help. I am receiving the following error message when I try to send an email to myself:

Delivery has failed to these recipients or groups:

'greg@sperbsherbs.com'
The email address you entered couldn't be found. Please check the recipient's email address and try to resend the message. If the problem continues, please contact your helpdesk.








Diagnostic information for administrators:

Generating server: BL2PR05MB066.namprd05.prod.outlook.com


IMCEAEX-_O=EX1_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+28FYDIBOHF23SPDLT+29_CN=RECIPIENTS_CN=Greg5@namprd05.prod.outlook.com
Remote Server returned '550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found'


Original message headers:

Received: from BL2PR05MB067.namprd05.prod.outlook.com (10.255.232.22) by
BL2PR05MB066.namprd05.prod.outlook.com (10.255.232.19) with Microsoft SMTP
Server (TLS) id 15.0.680.12; Sun, 28 Apr 2013 14:39:28 +0000
Received: from BL2PR05MB067.namprd05.prod.outlook.com ([169.254.2.100]) by
BL2PR05MB067.namprd05.prod.outlook.com ([169.254.2.100]) with mapi id
15.00.0680.012; Sun, 28 Apr 2013 14:39:28 +0000
Content-Type: application/ms-tnef; name="winmail.dat"
Content-Transfer-Encoding: binary
From: Greg Sperber
To: "'greg@sperbsherbs.com'"
Subject: Firefox
Thread-Topic: Firefox
Thread-Index: Ac5EHdl13OwIEqcZQCKAwb3wSSUzFg==
Date: Sun, 28 Apr 2013 14:39:28 +0000
Message-ID:
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach: yes
X-MS-TNEF-Correlator:
MIME-Version: 1.0
X-Originating-IP: [23.30.125.194]
Return-Path: greg@sperbsherbs.com