I was fixing an Outlook problem on my boss's laptop. I noticed he had a huge Deleted Items folder, so I decided to be helpful and empty it.
(Bare in mind that as head of IT he was a very technical person, and the only reason I was fixing the problem was that he had to go to a meeting.)
It turned out that his email filing 'system' was to delete any not immediately-relevant email, but leave them in the bin just in case he needed them later. Fortunately he understood that this was a carzy system, so he forgave me for deleting what was effectively his 'inbox'.
(I hope you have a better system now Malc!)