Find a duplicate e-mail address in Active Directory

We recently started seeing a lot of mails stuck in the submission queues and found that there were a few duplicate e-mail addresses in the environment. Most of the time we could not find the duplicate addresses in Exchange and had to search for the duplicates in Active Directory as some addresses were bound to AD objects.

To search for a duplicate address do the following:

  1. Open Active Directory Users and Computers
  2. Right click on your domain name and click on find
  3. Next to find choose custom search (see below screen shot)
  4. Then click on the Advanced tab (see below screen shot)
  5. Under “Enter LDAP query:” type the next search query (see below screen shot)
  6. proxyaddresses=smtp:useremail@domain.com
  7. Click find you you should find all objects with the duplicate address.

Screen Shot of the LDAP query in when looking for a duplicate address


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