Non-deliverable message from new hire email address.

I have a user here who's email address is producing the error message below when some users attempt to send to her.

Her AD account and mailbox are new (and have been deleted then recreated for good measure). But the message still persists.

Delivery has failed to these recipients or groups:

"Kacie Matthews
The e-mail address you entered couldn't be found. Please check the recipient's e-mail address and try to resend the message. If the problem continues, please contact your helpdesk.


Diagnostic information for administrators:

Generating server: DEN-EXC-006.res.lan

IMCEAEX-_O=RES_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+28FYDIBOHF23SPDLT+29_CN=RECIPIENTS_CN=Kacie+20Matthewsef4@res.lan
#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##

Original message headers:

Received: from DEN-EXM-001.res.lan ([fe80::ec5f:cc84:15f4:ab6d]) by
 den-exc-006.res.lan ([::1]) with mapi id 14.02.0347.000; Wed, 11 Sep 2013
 12:59:36 -0600
Content-Type: application/ms-tnef; name="winmail.dat"
Content-Transfer-Encoding: binary
From: Damon Maranya <Damon.Maranya@res-americas.com>
To: Kacie Matthews <Kacie.Matthews@res-americas.com>
Subject: test
Thread-Topic: test
Thread-Index: Ac6vIQ6F/uxDraiPRR+7m0hcvdFamg==
Date: Wed, 11 Sep 2013 12:59:35 -0600
Message-ID: <9D3E8284FA264147BB2D8A7DA65559CF5234DF1C@DEN-EXM-001.res.lan>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator: <9D3E8284FA264147BB2D8A7DA65559CF5234DF1C@DEN-EXM-001.res.lan>
MIME-Version: 1.0
X-Originating-IP: [172.21.131.88]"

Anyone have any idea why?


Thanks,

Damon M.