Using Classic Outlook on Windows for personal email, calendar, and contact management
Jeff,
Please skip the Powershell steps that In App provided. They were trying to test turning off the feature before actually turning it off from the service.
A root cause the Outlook Dev mentioned was he saw that the Outlook Profile key PR_PROFILE_USER_MANAGED_ALIASES_W somehow had too many aliases and Outlook was not handling that properly causing the error. I believe he said the limit was 30 aliases before it might cause issues. The theory is if you create a new Outlook profile that profile property will get reset back.
That PR_PROFILE_USER_MANAGED_ALIASES_W is supposed to map to what you see in the From drop down when you write an email. If you create a new email and click the From dropdown, do you have many aliases listed there? Were these aliases you added or created by Outlook? I know a lot of people use aliases for work e.g. sales, support, etc. Just curious why I am not causing a repro when I added a bunch of aliases to my account. There must be something more to it.