Microsoft is in the process of rolling out a new Outlook experience for all Outlook users.
Note that if you activate the New Outlook experience, the Smokeball Outlook Add-in may stop functioning properly. We are currently in the process of updating the Outlook Add-in to be compatible with New Outlook.
If you have enabled New Outlook, you can follow the steps mentioned in Microsoft's article to switch back to Classic Outlook and continue using Smokeball Outlook Add-in.