Configuring preferences and options in Outlook.com
I contacted the Outlook.com team through Twitter - here their response:
We value your feedback on this matter. In this case, we encourage you to submit this concern using the Feedback Hub: https://msft.it/6014TwFVC. When you submit a feedback item we gather additional details and information about your issue that will help determine what's causing it and address it. Feedback items regularly receive Microsoft responses on the submissions in the Feedback app so you can see what we are doing about your feedback. We hope this information helps.
Feedback Hub app is for reporting issues and giving feedback related to Windows and apps, it is not related to Office 365 at all.