A number of people have inquired about the .pst file format on this forum in the past, and at that time we stated we would provide an update if the .pst file format specification becomes available. This week we announced our documentation plan for the .pst file format specification on the Interoperability @ Microsoft blog,. If you are interested in actively participating in the review of preliminary drafts of the .pst file format specification, send an email message to pstinfo@microsoft.com and then we will contact you when a preliminary draft of the specification is ready for broader review. If you only are seeking the final version, we anticipate releasing the .pst file format specification in the first half of 2010 under our Open Specification Promise.