Ambiguous / Automatic Name Resolution in Exchange
Exchange searches various attributes like Name, Surname, Display Name, Mailbox Alias etc… in Global Catalog / Active Directory when you enter some character in To:, CC: or BCC: fields of Outlook and press CTRL + K, it gives you result with any or all matching addresses to your search. This process is called as a Ambiguous Name Resolution or Automatic Name Resolution.
You can also add your required properties/attributes, such as Employee ID, to ANR searches so when anybody knows the Employee ID of any person then they can get the email id with it and for that you need to customize the schema attributes.
Note : These Schema changes are forest-wide and It CAN NOT be reversed once you change it so make sure you took proper decision.
Now lets consider I set Custom Attributes 14 as a Employee IDs for all users in my company and I want to add this attribute in ANR process.
Now you need to change the Schema so you need to register schmmgmt.dll to access it, then Open Active Directory Schema snap-in into MMC and go to Custom Attribute 14 (schema attribute name is extensionAttibute14).
You have to select below three checkbox.
1. Index this attribute in Active Directory – To index the attribute in Active Directory so that search result is fast.
2. Ambiguous Name Resolution (ANR) – To add the attribute in ANR process.
3. Replicate this attribute to the Global Catalog – To replicate the attribute in GC so it is available forest wide otherwise it is restricted in single domain.
After doing these changes wait for sometime to update and replicate across the forest and then you can search for user with Employee IDs. eg. search for Emp ID starts with 18.