Still the closest I've come is Zimbra + zpush. Zimbra isn't fantastic, but it covers a lot. zpush is for the mobile part, and allows to you to connect to Zimbra

Still the closest I've come is Zimbra + zpush. Zimbra isn't fantastic, but it covers a lot. zpush is for the mobile part, and allows to you to connect to Zimbra as if it were an exchange server.