I dont believe that their are any files that can be permanentlyerased because a lot of the information is stored on the hard driveand cannot be erased. You can send all your deleted mail to therecycle bin so if necessary you can restore the files at a latertime. The files can also be deleted by pressing shift + delete andthis will erase the files. I have seen where you have a bankaccount and you are signed up for online banking and theinformation gets cross up and you get someone else informationwhich is suppose to be confidential the banks will try to catch itbut the information has gone to another person and you have to thenmake changes to all your accounts. We can use drive cleaners to trykeep this information to prevent these types of incidents and wecan use secure sites to prevent confidential information fromgetting into wrong hands.