The main reason why you might be having trouble sending emails from PowerPro when previously you may not have will be because you are part of Microsoft's Insider Program

The Insider Program gives you access to a 'beta' test version of Outlook which Microsoft allows early adopters to use to help them iron out any bugs they may find
The Insider Program will also allow you to preview the test version of the application 
The preview slider button is located in the top right corner of Outlook where you can turn it on/off as you wish 
More information about trying the new Outlook can be found here

 

The beta test version of Microsoft Outlook is not compatible with PowerPro and it is recommended to opt out of the Insider Program so as to remain compatible with PowerPro

For more information on how to leave the Insider Program click on this link