The default Search Dialog of Microsoft Outlook
looks as follows

In this post I will add an additional field in the search
dialog. This field can be a field that already exists in active directory or can be an MS Exchange Extension Attribute.
To change this window, first go to the Exchange
System Manager. It is located on the machine where exchange server is
installed. Drill down to the following location

If you check the properties of Search Dialog
you will see all the attributes available on the search contact window. Here you
can remove fields which are not required and add your custom fields or relevant
fields.

Here you can change the X,Y position, length, width, height
and the multiline property of the fields.
Now if you go and check the search window, a new field will
be displayed there. Now the million dollars question, how to populate this
field? If someone wants to use the default UI of AD for population these
additional fields, he will have to write an extended UI for AD using VC++ or
C++. However if you don’t wana do that then create users programmatically and
populate you required fields. The catch to this method is that your AD admin
will not be able to view these fields using AD UI.
