Locating Duplicated SMTP Proxy Address in Active Directory

I am trying to add a user account in AD which is fine but when I try and change the email alias it tells me that the address is already in use. I am having a hard time finding which user has this alias. I have tried to query

AD for the email address but cannot find it. What can I use to find the user in AD that is using the alias?

Solution 1:

• First go to ADUC (active directory computers users)
  
• Click, start, run, type DSA.MSC
  
• Click on Icon (find objects in active directory) Top far right corner
  
• Click Drop down menu and pick Custom Research, Click Advance, in the LDAP queries
  
• Type following
  

ProxyAddresses=SMTP:oz@smtp25.org (Modify the name oz and the @Smtp25.org part to your scenario)

Solution 2:

Download Adfind.exe

Run below command to locate the SMTP Proxy address

adfind -b dc=SMTP25,dc=Net -f (proxyAddresses=smtp:oz*) name proxyaddresses

adfind -b dc=SMTP25,dc=Net -f (proxyAddresses=smtp:oz*)

Best

Oz Ozugurlu