I was struggling with converting a .pst archive to a .dbx (so I could bring a huge .pst archive over to Mac OS X and Mail.app). It turns out to be really easy.
1. Open Outlook (in my case Outlook 2003) and open your .pst archive. Next, go to Tools->Email Accounts, click the radio button for “View or Change existing email accounts”, and then under “Deliver new email to the following location” you should choose the name of your .pst archive (in my case it was called “Personal Folders” (see screenshot). You’ll get some warning about all new incoming mail going to your .pst archive, but just continue, as we’re almost done with the repugnant odor otherwise known as Outlook.
2. Open Outlook Express (if you can’t find Outlook Express, go to Start->Run, type in msimn.exe, and press OK to launch it if it exists somewhere on your machine), choose File->Import->Messages->Outlook and then choose the mailbox you want to import (or all of them if you must).It took about an hour and a half, using a speedy IBM ThinkPad T42, to pull in an archive over 1 GB, but it did it eventually…
3. Before you quit Outlook Express, go to Tools->Options->Maintenance->Store Folder and note your file path to where your .dbx files are kept (mine is “C:\Documents and Settings\bschwie\Local Settings\Application Data\Identities\{3203D4E4-3933-4654-8ACC-63655A457D5D}\Microsoft\Outlook Express”).Next, to convert the .dbx files into .mbox files, grab “DbxConv”, a DBX to MBOX converter by Ulrich Krebs. Toss DBXconv into the same folder as all of your .dbx files, open a DOS prompt, navigate to the directory that contains the folder full of .dbx files and DbxConv, and then run the following command:dbxconv -mbx *.dbxDepending on how large your .dbx files are, this may take a while (I had a 1.5 GB file that took a half hour). After they are converted, rename the file ending for each file from .mbx to .mbox…
4. After the .dbx files are converted, move the folder containing the .mbx files to your Mac (finally!). On your Mac, renamed all the .mbx files to .mbox. Fire up Mail on your Mac and go to File->Import Mailboxes->Other and then navigate to the folder containing all the .mbx files. All the .mbox files will be grayed out, but just click the “Choose” button and the next window in Mail will show you all the .mbox files it can convert (it will ignore the .dbx files if they are present). Click the OK button to begin importing… Again this may take a bit depending on the processor inside your Mac.Alternative ending… If you aren’t able to get DBXconv on to your PC you can fire up Entourage on your Mac, instead. To go this route, skip steps 3 and 4 above and while you’re in Outlook Express, make a folder on the desktop and drag all the mail messages that you want to convert to the folder on the desktop. Then, transfer this folder containing all your messages in .eml files to your Mac. Fire up Entourage and drag and drop these .eml’s. Once they’re all converted (Entourage may appear to lock up, just be patient), you can export from Entourage to an .mbox file for Mail.