A previous admin had created a mail box that forwarded to a distribution group. I did not like the implementation so removed the mailbox. I deleted the group in AD and then used power shell to delete the disconnected mailbox.
I then created a distribution group properly, and mail enabled it for external senders. I did however use the same email address for the distro that was used for the traditional mailbox that I deleted.
External senders can send to it fine. When internal senders try to send to it, they get a kick back.
I have cleared the old address references from the Outlook cache on my test machine with no luck.
The NDR is below
Help Desk
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: ELM.domain.local
IMCEAEX-_O=BUSINESS+20NAME_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+28FYDIBOHF23SPDLT+29_CN=RECIPIENTS_CN=Help+20Desk5d0@domain.com
#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##
Original message headers:
Received: from ELM.domain.local ([fe80::e09e:2497:475f:4e37]) by ELM.domain.local
([fe80::e09e:2497:475f:4e37%11]) with mapi id 14.03.0195.001; Fri, 21 Nov
2014 20:37:49 -0500
Content-Type: application/ms-tnef; name="winmail.dat"
Content-Transfer-Encoding: binary
From: Jonathan Anderson <janderson@domain.com>
To: Help Desk <helpdesk@domain.com>
Subject: TEST
Thread-Topic: TEST
Thread-Index: AdAF9OlTqCqosSopTui6Xt5yo34cvg==
Date: Fri, 21 Nov 2014 20:37:49 -0500
Message-ID: <206B5E939DDF2D468FAE2F57D4CBB6C605CEE7@ELM.domain.local>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach: yes
X-MS-TNEF-Correlator: <206B5E939DDF2D468FAE2F57D4CBB6C605CEE7@ELM.domain.local>
MIME-Version: 1.0
X-Originating-IP: [x.x.x.x]
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