Extracting email address for the who database?
Do you mean to export all the contact's email address from CiviCRM into csv file? If so you can do Find Contacts and export the result into csv format.


Navigate CiviCRM >> Search >> Find Contacts
Select list of contacts to export and from action dropdown select 'Export Contacts' options.
On export screen select 'Select fields for export' and proceed
On 'Select fields to export' page from the first dropdown select Individual and then Email and Primary from the drop drown besides it.
Click on export button.


HTH

Pradeep