I have some old files (mostly emails) I want to get rid of so that they are gone for good and not recoverable. These are files that I have deleted in the past non-securely by simply deleting them from windows. As they were deleted the old fashioned way, I ran Ccleaner to wipe free disk space, assuming it would get rid of them. However, when I use software like Recuva, I'm able to find and recover those files even after an MFT free space wipe with Ccleaner.
Recuva shows these files as unrecoverable and I can see that they have been previously overwritten by other files. The files that have overwritten these seem to mostly be newer e-mail files or random windows files, so I assume this is done by windows when the disk space is needed.
Here is the problem though - they show up as unrecoverable in Recuva, but so far I have been able to recover every single one I've tried. I can recover the email messages and even attachments on them show up. so clearly they are not completely overwritten, but I don't understand how/why.
if I try to do a secure overwrite with Recuva on those files, it will not do so because they are "previously overwritten". Yet they are not, because I can still recover them. Ccleaner apparently won't do anything to them, I assume because they are supposedly overwritten already, but again, they seem not to be.
So any ideas on what to do? I wan't to remove all traces of these files. I obviously cannot use a shredder on those files because they are in theory overwritten so I can only see them in recovery software, but still they remain recoverable. Would using another wiper such as Killdisk to wipe free space help? Do I need to nuke the entire drive? Do a clean windows install? or will I still have traces left? replace the hard drive and torch the old one in flames?