Email It In has just added support for the Egnyte hybrid cloud storage service. Unlike the other services Email It In supports (Google Drive, OneDrive and Dropbox), Egnyte allows their customers to maintain storage on-premises, as well as providing a cloud storage service.
To add Egnyte support we worked very closely with both Egnyte and their users to ensure we offered the best service possible. Users of Egnyte can sign up for free trials at https://emailitin.com/