eFiler does exactly what it says on the tin - It allows you to store email messages in your mail client folder structure so that they appear when you open Outlook. This way you don't lose them if you delete them or move them around. If you use multiple mail clients it means you can view them from wherever you happen to be. You can use eFiler to find the files you want to save in your cloud storage account, and you can search through those files. If you're on mobile devices, eFiler will let you download emails into your device (including attachments) and send new emails right away. As for the interface, it is easy to navigate and it is easy to add and remove items. The best thing about eFiler is that it is totally free!