How To: Merging multiple PST files in Outlook into one Master archive

Note: This entry has also been posted on my company's website here:

A customer had gone through several computers with several iterations of Outlook.  Per Microsoft’s default preferences (grumble grumble), each different Outlook profile insisted on creating its own Auto-Archive folder in the user’s Application Data directory.

Obviously, this is bad from a backup perspective—what had prompted this question was the fact that her old computer’s hard drive had died, having succumbed to the “click of death.”  She lost everything that wasn’t backed up on the network drive (including, presumably, the latest iteration of her local Auto-Archive folder).  We continue to suggest to all customers that they:

1) Turn off Auto-Archiving

2) Manually create an archive PST file on the network drive (which should be backed up nightly)

3) Name the PST file something useful (like 2008 Archives)

4) Drag-and-drop items as needed into the new archive folder, making sure to not let it get too large—if it does, repeat steps 2-4 to create a new archive and break it out further

At any rate, I was looking for a way to combine multiple PST files into one—in order to consolidate all of the old Auto-Archives (some of which had thankfully been moved to the network drive prior to her hard drive crashing) from previous Outlook profiles into one master archive file.

Note: I made sure that combining the files wouldn’t create an archive larger than 1-2 GB.  There are different schools of thought on “what Outlook can effectively handle” regarding the size of archive PST files—I tend to play it safe and break things out into multiple smaller archives, rather than one large one.

Unfortunately, I couldn’t find any truly freeware applications out “in the wild.”  Everyone wanted $29.99.  I was convinced I could do it for free.

Note: The next steps & screenshots are from Outlook 2010.  Steps will differ in Outlook 2003 & 2007.

For my test, I created three archive files: 1, 2 and 3.  Within each, I created subfolders.  Archive 1 had folder 1.  Archive 2 had folder 2 and folder 1.  Archive 3 had folder 3, folder 2 and folder 1.  Folder 1 always contained copies of the same item (three in total once merged—if it doesn’t eliminate duplicates).  Folder 2 also contained copies of the same item (though different from the item in folder 1)… for a total of two copies once merged).  Folder 3 contained one item:


I then created a “Master” PST on the network drive that is to contain the merged contents of archives 1, 2 and 3:


Once named & saved it to the network drive, we can see that it’s blank:


So, with “Master” highlighted in my Folder List view, I went to File > Open > Import:


I then said “Import from another program or file”:


…and “Outlook Data File (.pst)”:

Unfortunately, as I discovered, you have to close the PST file first:


…so after closing the file:


…I ran the same steps again, making sure to select “Do not import duplicates”:

…and match the options below:


I then repeated the process for archives 2 and 3… closing the archive, importing into the Master archive, and checking the contents:

At this point, I moved the physical 1, 2 and 3 PST files to a folder marked “Old Archives – Merged into Master Archive.”

The final (and most important) step is to change the Auto-Archive location in Outlook to be the same as the Master archive PST file:

Now, all of the archives are in one Master PST file, safely tucked away on a backed up network drive.