Duplicate Email Address Exists in Exchange

Sometimes when you try to add an smtp address to an object in AD, you get the following error due to the fact that the address already exists:

This email address already exists in the organization.  ID no: c10312e7


Active Directory Users and Computers snap-in can be used to find the object that owns the address.


To do this, follow these steps:


1.    Run Active Directory Users and Computers.

2.    Right-click the domain object and choose Find from the context menu. This will bring up the Find Users, Contacts, and Groups window.

3.    In the Find drop-down list, choose Custom Search.

4.    Change the scope to Entire Directory

5.    Click the Advanced tab and in the Enter LDAP query: field, enter the following text: proxyaddresses=smtp:rwilliams@zixcorp.com  (use the email address that you are trying to add).  Notice that the attribute proxyaddresses is plural, i always forget that…

6.    Click the Find Now button and it will show you the object that owns the SMTP address.  It’s usually a public folder in my experiences.


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