While several programs exist to convert some formats such as Microsoft Outlook Express to Unix formats, Outlook users have a bit more of a challenge. One way to convert uses Mozilla Mail under Windows; another involves a more complicated method. Both are explained in this miniHOWTO.
The database format that Outlook uses for .PST files, called Jet, is documented at:
http://msdn.microsoft.com/library/techart/olexcoutlk.htm
Copyright (c) 2001-2004 by Greg Lindahl
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http://www.gnu.org/copyleft/fdl.html
I request that corrections and/or comments be forwarded to the document maintainer. If you're considering making a derived work other than a translation, I request that you discuss your plans with the current maintainer.
Use the information in this document at your own risk. I disavow any potential liability for the contents of this document. Use of the concepts, examples, and/or other content of this document is entirely at your own risk.
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You are strongly recommended to take a backup of your system before major installations, and backup your system at regular intervals.
Do not place your cat in a running microwave oven.
1.01: Fixed minor typo in inetd/xinetd startup instructions.
1.1: Added information about Kmailcvt, Mozilla, and how to get Outlook to talk to IMAP servers if it's in Exchange mode.
1.2: Added details about using Mozilla to do this same task
1.2.1: Fixed formatting typo.
1.2.2: Relicensed under the GFDL, more minor typo fixes.
1.3: Yet more minor fixes.
1.4: Information about TNEF stuff from Scott Phelps (thanks!)
A list of conversion utilities, many commercial, may be found at:
http://www.emailman.com/conversion/index.html
I've had a claim that the program Kmailcvt now converts Outlook mailboxes. However, I'm not 100% sure that this claim is true, since Kmailcvt definitely converts Outlook Express mailboxes, which are completely different from Outlook mailboxes. So, if you figure this out, please let me know.