MS Exchange stores the email addresses for all users and other entities within the Active Directory. Adding extra email addresses to users is actually quite easy and straight forward, UNLESS exchange suddenly gives you the error “This e-mail address already exists in this organization.”

Not a very helpful error message, but normally I’d think no problem, let’s just look for the address, but after spending about half an hour surfing through our AD I still hadn’t found the email address or the user it may be associated with it. All versions of searching were turning up blanks, but obviously this email address was still being used somewhere.

Multiple email addresses can be added for a user or folder – but its very hard to see which email addresses have been assigned to which entity – especially as there are 2 different management consoles dependant on the type of entity, and secondary email addresses are not easily visible without opening the entity that contains them.

Luckily, the active directory is an LDAP data store – and it is possible to run LDAP queries against it.

You can find what entity has the selected email address assigned to it by doing the following:

• Open the Active Directory Users and Computers Management Console
• Right Click on the domain > Select Find
• Select Custom Search in the Find field
• Select the Advanced tab
• To find the entity with the email address yourname@yourdomain.com for example, enter the following in the LDAP query field: (proxyAddresses=smtp:yourname@yourdomain.com)
• This will list the entity containing the email address entered.
• Wild cards can be entered within the email address (*) to return multiple matches.

I hope this helps some of you save some time, if you ever encounter a “rogue” email address in your system…