Corrupting your Outlook PST file

Couple of months ago, I accidentally deleted about 1600 emails, some of which were of quite importance. I could have lived without them, but I figured since PST files are basically databases, they will not be deleting emails for real, just flagging them as deleted

I googled around and found this nice tutorial how to get your files back.

The first obstacle I hit was a problem with long filenames. I don't know if my DEBUG.EXE is stupid, but mine wouldn't open a file over 8.3 characters. So I renamed my copy of pst file to something short and upon running again I hit "Insufficient memory" error.

F:\debug a.pst
Insufficient memory

I did a couple of tests and found out, that the size limit for DEBUG.EXE is 574816 bytes. Files larger than that will simply not fit. So if you have more than ten emails in your inbox, you will probably encounter problems as well :).

So I had two options what to do

1. Download a hex editor and edit it manually
2. Write a program for corrupting PST files

You already know, which option I chose. It wasn't the geekiness of it, but I figured, that I will be sending this program to my less tech savvy friends and giving them instructions will be much easier if I skip the part with hex editor :).

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[])
{
 FILE *f = fopen(argv[1], "r+b");
 int length = 6;

 unsigned char *a = (unsigned char*)malloc(sizeof(unsigned char)*length);
 memset(a, 20, length);

 fseek(f, 7, SEEK_SET);
 fwrite(a, 1, length , f);
 fclose(f);
 free(a);
 return 0;
}

Usage: In case you accidentally delete some emails, you need to

1. Turn Outlook off
2. Locate your PST file
3. Run corrupt.exe YourOutlookfile.pst
4. Start "c:\Program Files\Common Files\System\MSMAPI\1033\SCANPST.EXE" or whichever version you have.

For convenience purposes binary version follows corrupt.zip (7kB).

Thanks to Mark James for creating the amazing Silk icons.

Btw. my favourite hex editor is xvi32. It's really good, check it out.