Microsoft to open up the PST-file format

The PST-format is used by Outlook

Paul Lorimer, Group Manager for Microsoft Office Interoperability today announced in a blog-post that Microsoft is planning to open up the PST file format. The PST format is used when Microsoft Outlook stores data locally.

Many Outlook users are using PST-files to make backups of their data. However, as it is a proprietary format, the data cannot easily be imported into any other application. While there are projects dedicated to reverse-engineering the format (such as libpff), open documentation would be welcomed by developers world wide.

Once Microsoft provide the community with this documentation, we will most likely see a lot of applications taking advantage of this. As PST-files are notorious for getting corrupted as they grow in size, 3rd-party repair tools are likely to become a lot more effective (and free). In addition to repair tools, we are also likely to see native PST import in desktop applications such as Mozilla Thunderbird and Apple Mail, as well as in various cloud based solutions, such as Google Apps.

While one could interpret this as a step towards a more open Microsoft, there is also a chance Microsoft is planning to phase out the PST file format in favor of something else (such as Sharepoint). Right now it’s too early to tell. Regardless of which one it is, there are still a lot of people out there sitting on tons of old backups in PST-files.

Unfortunately the press release is lacking any dates for when Microsoft will starting providing the developer community with the promised specs. Hopefully this is more than just publicity stunt from Microsoft’s side. Perhaps we could even see a Microsoft equivalent of Google’s Data Liberation Front.