On the NEW Mail, Task and Appointment screens you will see an Address Book button.
This button opens a CRM address book dialog. Type on this and click "Go" (or hit return) and the system will search CRM returning the top 25 results from your CRM system.
Example of the SQL run to get the data for this address book ('frank' would be the search value entered in the filter)
SELECT top 25 * from vAcceleratorEmail WITH (NOLOCK) where pers_firstname like '%frank%' or pers_lastname like '%frank%' or pers_fullname like '%frank%' or emai_emailaddress like '%frank%'