The Internal Revenue Service (IRS) said it can't provide emails sent between 2009 and 2011 that were requested by congressional investigators because of hard drive crashes.

The agency said that emails stored on dead drives were lost forever because its email backup tapes were recycled every six months, and employees were responsible for keeping their own long-term archives.

The IRS had a contract with email backup service vendor Sonasoft starting in 2005, according to FedSpending.org, which lists the contract as being for "automatic data processing services." Sonasoft's motto is "email archiving done right," and the company lists the IRS as a customer.

In 2009, Sonasoft even sent out a Tweet advertising its work for the IRS.

The extent and exact details of the service that Sonasoft provided to the IRS aren't clear. But the company advertises its email archiving solution as "ideal for small and medium businesses, government agencies, school districts, nonprofit organizations using Microsoft's Exchange Server." And a document posted on its website describing its services says that its system "archives all email content and so reduces the risk of non-compliance with legal, regulatory and other obligations to preserve critical business content."

Sonasoft connection and IRS contract details first noted on Morgenr's Twitter account.

Update: Sonasoft's contracts with Treasury were pretty modest: about $5,556 in 2005, $24,706 in 2008, and $13,983 in both 2009 and 2010. And the company itself is not very large (it has a market cap of $4.4 million). So it's quite possible that the extent of its services were pretty limited.