To Do is Outlook Tasks
According to Microsoft’s help, all To Do tasks are stored on Exchange Online servers and appear in Outlook Tasks automatically. A flagged email becomes a task: the name comes from the subject, and the task opens the original email. This works only for mailboxes hosted by Microsoft (Outlook.com, Hotmail.com, Live.com or a custom domain on them), and when you turn the list on it fills with the 100 most recently flagged emails from the last 30 days.
The link is not complete. To Do does not show start and end dates, task status, completion percentage or multiple priority levels from Outlook Tasks. KIPRI has no connection to mail at all.

