If Microsoft Outlook 2016 or Outlook 2013 is not running when you double-click an .msg file, an earlier version of Outlook opens.
This problem can occur if you have Outlook 2016 or Outlook 2013 (as part of a Click-to-Run installation of Office) installed on the same computer as an earlier version of Outlook. If you perform a software update on or repair your earlier version Office, the file associations on your computer may be reset to that particular version of Office. For example, the following registry data shows the .msg file name extension is associated with Outlook 2010.
Most people that install Office 2016 or Office 2013 will install Office by using Click-to-Run. Because Office Click-to-Run does not uninstall any previous Office versions, you will be using Office in a coexistence configuration. If you do not need the earlier version of Office installed on your computer and you are only using Office 2016 or Office 2013 programs, you should consider uninstalling the earlier Office version.
Follow these steps to uninstall an earlier version of Office:
Exit any currently running Office programs.
Start Control Panel.
Click Uninstall a program.
Select the earlier version of Office entry in the list of installed programs, and then click Uninstall.
When you are prompted to confirm you want to remove the earlier Office version, click Yes.