VERIFIED SOLUTION i

How to setup the required configuration Test for viewing emails on multiple clients on Portrait Dialogue

Here is how to set up Test viewing of emails on multiple clients from within Visual Dialogue.
There are 3 steps.  
  1. In Dialogue Admin, Under [General Admin] / [Parameter Collections] / [Channel Parameters] locate the EmailTestingSupport setting. Set that value to "2". (Right-click the setting and choose Properties... to see a fuller explanation of the setting.
  2. Make sure you have your email channel correctly configured.
  3. After creating your message template in Visual Dialogue, in the Design tab, you'll see the round blue "Test" button with the triangle in it.  Next to that, there is an icon with a red flag and a checkbox labelled Test Email.  If you click that Test Email button, the email testing process is launched.  Note that this icon only shows up when you have already made the above EmailTestingSupport change in Dialogue Admin.
UPDATED:  April 21, 2017