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Securely deleting email messages can be important, but doing so in Microsoft Outlook is difficult, though not impossible.

I have Win XP Pro SP2 with MS Office Pro 2000 installed, and use MS Outlook 2000. In the Outlook I would like to be able to shred (not just delete) individual, old e-mails.

I have the necessary shredder software to do this but how can I find the individual e-mail files and where they are stored ? I don´t necessarily want to shred all old e-mails, but only specific mails.

I think that this must be possible, although I have not been able to find any relevant information on the Internet. Could you please give some advice and point me in the right direction?

We need to first clarify what you mean by "shredding", and then I'll explain why, in general, an external shredding tool can't work with Microsoft Outlook.

And then I'll explain what you can do instead.

What most people refer to as "shredding" a file is nothing more than a secure delete. The file is first overwritten multiple times with specific patterns of data so as to thwart any advanced data recovery techniques, and then it's finally deleted. There are both commercial and free tools to do this; my preference is the freeware sdelete utility from Microsoft and SysInternals.

The problem here is simple, though: shredders or secure delete utilities work on files.

Outlook does not store individual messages in individual files.

Instead, Outlook stores all of your email, calendar, contacts and the like in one big file, called a "PST" for Personal Store.

That means that you can't "shred" an individual message, because there's no separate file to shred. The message is just some data somewhere inside of your PST along with other information.

So let's look at the goal and devise an alternate way to achieve roughly the same thing.

"... you can't "shred" an individual message, because there's no separate file to shred."

The goal is simple: to delete a message from your hard disk in such a way that even advanced data recovery techniques cannot find it. That typically means obliterating with a secure delete or disk wiping type of function the hard disk sectors in which the deleted message was stored.

Since we don't know exactly what sectors those might have been, we have to take some extra steps.

Here's what I'd do for maximum security:

  • Delete the message in Outlook. As we know this doesn't actually delete the message, but moves it to the recycle bin with your Outlook PST.

  • Empty Outlook's recycle bin. This also doesn't really delete the mail, it simply marks the space previously occupied by the email as now being free and available for Outlook to put new messages and other things.

  • Exit as many other programs as you can. We want to make sure that the disk is used as little as possible for the next few steps.

  • Compact the PST. This really does delete the messages because it removes all the unused space from the PST. The unused space in the PST is returned to the operating system as actual free disk space.

  • Exit Outlook. We'll be making a copy of the PST shortly and we need Outlook to stop accessing it while we do so. We also need to make sure that it's not changing the PST during the next step.

  • Wipe the hard disk free space. Using a tool like sdelete, or some of the other free-space wiping or shredding tools, this ensures that the unused space on your hard disk is securely wiped clean. No files that used to be stored in the free space can be recovered. Part of the compaction process will have "moved the PST around" on disk, and the disk areas that used to hold your message could be part of the free space - hence you'll want to wipe 'em.

  • Make a copy of the PST. Locate your PST and in that same folder simply make a copy of the PST under a new name. The copy will make use of the free space we just wiped clean. Make sure you've done this properly before proceeding.

  • Shred or secure-delete the original PST. The problem this solves is that during the compaction process the PST may have been rewritten on top of the disk space formerly used by the message you're attempting to delete. That means that the secure wipe we just did of free space won't have obliterated all traces of the message. That's not good enough, and you actually want to shred or secure delete that region as well by shredding the PST.

  • Rename the copy you made of the PST back to the original name.

  • Restart Outlook

Unfortunately, based on other disk activity that still may have been happening while you were doing all this, there's still a tiny chance that a disk sector that held the message may have survived. If the sectors previously occupied by the message were taken by another program between the time the PST was compacted and the free space wiped, then that sector would never have been securely shredded. That's why shutting down as many applications as you can is important in this process.

The good news, though, is that the chances of that happening really are tiny. This process will give you a fairly high degree of confidence that the message you're attempting to shred is almost certainly, irretrievably, gone.

Article C3199 - November 1, 2007 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

6 Comments
Mark
November 1, 2007 9:13 PM

One little problem with this whole concept, though, is that the email is never truly gone. That message had to go through MANY computers before it got to yours, and each place it passed through MIGHT contain a copy somewhere. The sender's computer, the ISP servers, etc etc....Am I right on this one Leo?

John Hileman
November 2, 2007 12:45 PM

Mark is correct.

I don't have this version of Outlook, but use an older one at work. What I would do with that version is create a personal folder where I would drag and drop all emails meant for shredding. Then, with Outlook closed, shred that personal folder. Then with Outlook opened a folder for shredding could be created.

Leo A. Notenboom
November 3, 2007 10:09 AM

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Mark: yes, you are quite correct. This article focusses on removing all traces
from your machine, but there are a series of mail servers, not to mention the
original sender's computer, on which the email may still reside. Those are out
of your control.

John: I assume you mean personal store (PST) not personal folder. Moving to
another folder just moves it around within the same PST. In either case the
process of "dragging and dropping" an email is actually a copy followed by a
delete. That means that the email is still in your original email folder or PST
in some kind of deleted state, even after you move it to another. Shredding the
second PST doesn't remove the traces or the email that remain in the original
location.

Leo


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bittaljoshi
November 6, 2007 8:10 PM

it's good suggestion for the Outlook.
I thing yr good teacher me.

So send me yr every post links.

remo
February 6, 2009 4:34 AM

I have the same question regarding vista mail: is it possible to shred emails in the Vista Mail "deleted items" folder by, for example, adding this folder to ccleaner items to clean.

ERNESTO LIEBRECHT
December 13, 2009 6:54 AM

I am not even close to the security issue. When I delete email in new Outlook 2oo7 all what occurs is that Outlook draws a line on top of the deleted email, but the email is still there, right in front of me, with the remaining emails. It not not sent to the recycled mail bin! I presume this is a setting option. How do I change it?


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