every few months my inbox gets "deleted", only no mail ends up in Trash so recovery of deleted items does not work, they are all just gone. Right now i only have mails from the last two weeks, all others disappeared on me for no reason. There was no rule set to delete all, there was no action taken. I have outlook setup on Nexus 7 in the Outlook android app, on iPhone and on Mac as POP with "Leave original on the server".

This isn't the first time it happened.