A cloud-based task management app from Microsoft that helps users organize and manage daily tasks across devices.
Hello @John Pattinson
To make sure we are on the same page and I understand your concern correctly for appropriate information, you can send me the screenshot of this issue here in your reply.
Along the way, as I have tested in my Microsoft To Do in web version with my flagged email, I can still see the button to open in Outlook as below image. When I click on this button, it can open in Outlook accordingly.
You can try again in the web version to see if this issue is still persists.
If you still need my assistance, please come back with screenshots or any additional details so I can review it again and see if there’s anything more I can help you with.
Have a nice day!
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in "our documentation" to enable e-mail notifications if you want to receive the related email notification for this thread.