It would be nice if the local cache would actually update as you delete emails from your inbox. After I cleaned up my inbox, my local cache, located in Other Data on iOS, the cache would not clear itself. It just ate up my local space and would not let me reclaim or reuse it. I deleted the app, and reinstalled yet still ended up needing to erase my phone and restore from backup. Very annoying and inefficient. If I remove data from my inbox, which is cached locally by default, as I move mail to other unsynced folders to store them, that local cache should then decrease in size. Maybe just give us the option to not locally cache any folders, I would be very happy with that, and would still give the ability to use my devices hdd and owa as a web based app. This is very annoying