Why is Microsoft opening up its Outlook file format now?

On October 26, Microsoft officials announced they were planning to open up the Outlook Personal Folders .PST file format and making it freely (and safely) licensable. What no one has said so far is why is Microsoft doing this now and who will likely benefit from the move.

The file formats are due to be published in the first half of 2010. According to Network World, the Redmondians are publishing only documentation for the .PST format for Outlook 2010, not previous versions of Outlook.

Microsoft officials are saying that the decision to post the documentation for the .PST file format came from customers and partners. When I asked today what led to the decision to open the file formats, I received back the following statement attributable to Paul Lorimer, Group Manager, Microsoft Office Interoperability:

"Data portability has become an increasing need for our customers and partners as more information is stored and shared in digital formats. Customers were specifically asking for solutions to further improve platform-independent access to email, calendar, contacts, and other data generated by Microsoft Outlook."

I asked my followers on Twitter this morning if anyone out there was interested in using the .PST documentation for their own purposes. Not that this was a definitive or scientific survey by any means, but I got no responses -- other than a few people speculating that Google or Facebook might want to take advantage of the new open format to make their wares more Outlook-compatible.

I asked a couple of analysts for their take on why Microsoft might be opening the .PST format. Rob Helm, an analyst with Directions on Microsoft, sent me the following response via e-mail:

"I suspect this decision came out of the European Union interoperability investigation. That investigation was launched in Jan. 2008 and covers the Office file formats and more generally, how interoperability affects competition with high-volume Microsoft products like Office. Microsoft seems to be moving toward a settlement that would close the investigation. The competition commissioner has said she would like to wrap her investigations into Microsoft before she leaves her post, and Microsoft would be happy if she pulled it off."

Helm said he expected some of Microsoft's competitors might want to make use of the newly documented formats.

"The big winners (from Microsoft's move to open .PST), will be vendors who want to compete with Exchange or Outlook. A lot of Outlook e-mail is lying around in .PST files, and competitors will be able to pick off users more easily if they can bring that mail into their own systems. The winners might include IBM Lotus, Oracle, and Google, and Cisco (which bought PostPath, an Open Source Exchange competitor)."

Helm added that he believed Microsoft is trying to wean large customers from storing mail in .PST files or file systems "because doing that makes it hard for organizations to back up all their e-mail, enforce e-mail retention policies, and locate relevant e-mails during legal discovery." He added that he doubted that this was the main reason Microsoft opened the format.

Rob Sanfilippo, another Directions on Microsoft analyst had some related observations. Sanfilippo noted that there are already a lot of third-party tools that access .PSTs and do things like repair and ennumeration through their contents, "so the format has been reverse-engineered long before being published by Microsoft."

Sanfilippo added that .PSTs "are used most frequently for archiving purposes and Exchange Server 2010 includes a new server-based Personal Archive feature that gives users a separate mailbox to use for archiving on the server instead of using a PST." He said this gives weight to the aforementioned idea that  Microsoft is trying to help organizations get users off PSTs and onto server storage."

There's nothing shameful about Microsoft opening up its Outlook formats in the hopes of appeasing antitrust regulators (if this is, indeed, why the Softies are doing this). But if this is the reason, why not say so, instead of leaving us skeptics to piece together later the real reasons behind their open promises?

Update (October 29): It took a couple of days, but Microsoft officials are now saying that the company never discussed the opening of the PST format with the European regulators. When I asked two days ago whether there was an antitrust connection, a spokesperson said that Microsoft had no comment. But today, the spokesperson said it was nothing other than customer and partner requests that led to the decision and not anything or anyone connected with the EU antitrust case.

Microsoft customers, partners and competitors out there: Do you care about the opening up of the .PST format? Why or why not?