Using New Outlook on Windows for professional communication and productivity
I answered my own question about why Outlook 2016 starts at boot when it is not in any startup list. I still do not know why it happens, but I was able to stop it from starting automatically. In Windows 10, by going to Settings >> APPS and looking for Office in the App list, I found two entries for MS Office, one for (Office) New Outlook and one for Office 2016. By UNINSTALLING the offending 2016 entry, it no longer starts at boot. I credit information from tenforums in this topic for the APPS information.