XADM: Finding Ambiguous Recipients or Recipients That Have Duplicate Addresses

Article translations Article translations
Article ID: 251152 - View products that this article applies to.
This article was previously published under Q251152
This article has been archived. It is offered "as is" and will no longer be updated.
Expand all | Collapse all


When you send an e-mail message to a known Exchange Server address, you may receive a non-delivery report (NDR) similar to the following:
Date: Mon, 17 Jan 2000 16:49:25 -0500
From: System Administrator<postmaster@testdomain.Microsoft.com>
To: user@testdomain2.microsoft.com
Subject: Undeliverable: test

Your message

  To:      testuser@microsoft.com
  Subject: test
  Sent:    Mon, 17 Jan 2000 16:48:45 -0500

did not reach the following recipient(s):

testuser@microsoft.com on Mon, 17 Jan 2000 16:49:22 -0500
    The recipient name is ambiguous.  
      The MTS-ID of the original message is: c=US;a= 
    MSEXCH:IMS:Microsoft:testdomain:SERVER1 0 (000C0595) Ambiguous Recipient
You may also receive the following error message when you try to create a recipient by using the Exchange Server Administrator program:
This e-mail address already exists in this organization Microsoft Exchange Administrator ID no: c10312e7
If the message is SMTP based, an event ID 10000 similar to the following may also be logged in the application event log of a server that hosts an Internet Mail Service:
Event ID: 10000
Source: MSExchangeIMC
Type: Error
Category: Addressing
Description: A message was not delivered because the following address was not unique:


This issue can occur because addresses must be unique across an Exchange Server organization, and so an address (for example, testuser@testdomain.microsoft.com) can only exist once in the organization. However, if the same address is created on two separate servers before replication is established or before replication has time to finish, it is possible to have two objects with the same address.


To resolve this issue, export the global address list from the server that is producing the error. Make sure that you include mailboxes, distribution lists, and custom recipients, as well as hidden objects. Also make sure that "E-mail Addresses" and "Secondary-Proxy-Addresses" exist in the header of the export file with the other fields to be exported. Import the .csv file that is created into Microsoft Excel and search for the location of the conflicting directory entries. You can then alter or delete the objects, as appropriate.

More information

For additional information about how to export the directory, click the article number below to view the article in the Microsoft Knowledge Base:
155414 XADM: Bulk Import/Export FAQ
If the initial export does not produce the objects that you want, you may need to export the e-mail addresses that are associated with Public Folder objects. For additional information about how to export the e-mail addresses that are associated with Public Folder objects, click the article number below to view the article in the Microsoft Knowledge Base:
185018 XADM: How To Export Public Folder Directory Data To A CSV File


Article ID: 251152 - Last Review: October 26, 2013 - Revision: 5.0
Applies to
  • Microsoft Exchange Server 5.5 Standard Edition
kbnosurvey kbarchive kbprb KB251152

Contact us for more help

Contact us for more help
Connect with Answer Desk for expert help.
Get more support from smallbusiness.support.microsoft.com