This just started happening in the last three days.  Emails are received in my Outlook Web inbox and stay there for 10 minutes or so then automatically get sent to the POP folder.  I do not have any rules for handling messages in my settings and the "Don't let devices or apps delete messages" box is checked.  This is of course also happening on my iPhone & iPad.  Very frustrating- my inbox is now totally empty when previously there were forty or fifty emails there.  They have now all been shifted to my POP folder.  Help!!