Article ID: 280765 - View products that this article applies to.
This article was previously published under Q280765
When you create a new user in the Active Directory Users and Computers snap-in and add an address in the Create Exchange Mailbox box, you may receive the following error message:
This e-mail address already exists in this organization.
This issue can occur if an object in Active Directory already has the address that you are attempting to add to the user's e-mail addresses list.
To resolve this issue, use either of the following methods:
Repeat the same process for public folders, contacts and groups, but use the following modifications:
Method TwoIf you have completed method one, and you did not find an e-mail address that is the same as the address that you want to add, use Network Monitor to do a trace between the Exchange computer and a workstation that has System Manager tools and Active Directory tools installed.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
148942In some scenarios, such as an ASP hosting scenario, there may be a need to create mail-enabled contacts in different OUs that have a common SMTP alias. EXAMPLE: CompanyA and CompanyB, both customers of an ASP, have their own address lists and cannot view the other customers' address lists. Both these companies have a common client, with common contact information. Using Active Directory Users and Computers, they cannot both create a contact with the same SMTP alias.
(https://support.microsoft.com/kb/148942/ )How to capture network traffic with Network Monitor
To resolve this, do not create the contact with Active Directory Users and Computers, but use the ADSIedit MMC snap-in or ADSI scripting (potentially from a web-based interface) to carry out this task. The fields to modify are "mail", "proxyAddress", and "targetAddress". Those fields can be modified to enter SMTP aliases that exist for other contacts in other OUs without error.
Article ID: 280765 - Last Review: October 25, 2007 - Revision: 4.3