Will stored emails on mail app be lost if I restore from a IPSW I no longer have access to the mail server to which my email client was connected. I am considering upgrading from iOS 8 to iOS 9.0 using an IPSW (not thorough the normal update which will take me to iOS 9.1). My concern is regarding the already downloaded and cached mail from the Exchange server which is currently accessible. Will it still be accessible after the restore? (i.e. does the application and data backup also store the emails already downloaded or does it rely on downloading them again from the server?)
You can't update to 9.0, Apple is no longer signing 9.0.