[junto]

Try http://owncloud.org/. Run your own cloud server. Files, contacts, calendars, loads of third party integrations (email via RoundCube: http://roundcube.net/).

I'm running mine off a Synology DiskStation that sits at home. Mobile clients for Android and iOS. Sync clients for Windows, Mac and Linux (plus source code if you want to write your own): http://owncloud.org/sync-clients/

You could point OwnCloud at the same folder as Dropbox. Both monitor the same folder. Double backup.

http://www.lifehacker.com.au/2013/04/how-to-set-up-your-own-... http://jamieflarity.com/technology/owncloud-and-email/