If you have enabled the ‘Flagged email’ option from settings in To Do, then any email you flag in Outlook will show up under the ‘Flagged email’ smartlist.
From the Outlook web app, you can create a task out of an email by right-clicking —> Advanced actions —> Create task. You can also select a message in the body of an email and create a task out of it.
An error occurred while saving the commentSteffen commented
Why can I not open a mail from ToDo in the outlook App. The mail is always opened in a Browser Window. But I will open teh mail driect in the Outlook App.