How to set up the Filter?
Select the Email List that you wish to filter. Under List Maintenance select the Email Filter option:
Enter in a name for the Filter:
Enter in the values for the Custom Variables based on which you wish to filter the list:
How to send only to the filtered email addresses?
Under Send Email Invitation select the list and click on the Send Email Invitation button:
From the Filter drop menu select the saved filter and send: