How can I get a list with all my Clients email addresses?

To get all the clients emails go to the client tab, and from the drop down menu go to the Advanced Contact Search. Once in there select 'Type = Client' and click in the Company field. Hit enter to get a list of all client contacts. Make sure you have the 'Maximum Hits When Searching' set to 'No Limit' (this may slow down performance a bit). In the 'Edit View' (access in the search result pane via the black arrow drop down in top left corner) choose to show the email address. To finish click on the 'Open As Spreadsheet' Button in the bottom right corner of the table.