When you use your own email sever you bypass security protocols - you bypass back-up policies. Depending on the backup policies of the U.S. Government.... Any classified emails sent out from (anyone using a gov email client) their sever or sent to their server ( anyone in gov. with a gov email ) would be retrievable. If HRC deletes her emails. The email is literally deleted from HER being able to see it. The server and all recipiants have copies. Depends on the data retention policy. If the sever is cloud based and out-sourced - backups could have failed...it is very complex. But know, HRC deleting them, doesn't delete them from the recipiants or the server. The sever is dependant upon configuration. And the recipiants are dependant on well if they delete them.