Microsoft introduced linked inboxes to Outlook Mail and Calendar for Windows 10 Mobile late last week, allowing users to link all their mail accounts into a unified inbox. However, a minor update that was rolled out yesterday was causing the app to constantly crash.
Microsoft has amended the issue by rolling out another update to Outlook Mail and Calendar, which removes the linked inbox feature. It is likely the new addition was causing the instability in the first place, so its removal means that users will at least be able to use the app now.
We'll let you know once the feature is re-introduced into Mail and Calendar.
Thanks cheeyong for the tip!