Hello, I've recently downloaded this plugin and its working very good. I want to add that it doesn't seem to work whith already send messages but instead you have to compose a new one.
These are the steps:
1. Compose new message
2. Add the recipients
3. Click on the 'outlook freeware' tab
4. Click the Run button
5. Select 'Send Messages Personally'
6. Click Run
After that you should see outlook starting to send mails '1 of 65' ...
Hope I could help