Last October, in the name of interoperability, Microsoft announced plans to make the Outlook Personal Folders .PST file format freely and safely licensable.
On May 24, Microsoft took a step along that path by making available for download two .PST interoperability tools. The pair -- a .PST Data Structure View Tool and a .PST File Format Software Development Kit (along with the related technical documentation) --are available under the Apache open-source license.
Here's Microsoft's description of the new tools:
"The .pst Data Structure View Tool is a graphical browser of internal data structures for .pst files that enables a developer to better understand .pst file content. The .pst File Format SDK is a cross-platform library that allows developers to read data stored in .pst files and develop applications accessing the data. In the near future, the capability to write data to .pst files will be added to the SDK."
Microsoft officials denied last year that they were opening up the .PST format due to any influence from or pressure by European antitrust authorities.