as someone who works in IT and has managed my company's email services and networks for many years, here's my perspective
Government run organizations have regulations and compliance laws that mandate all email be archived. There are appliances that do this before email even hits the mail server. Barracuda appliances are one example of this. it is a set it and forget it type of machine. all incoming/outgoing emails are archived and forwarded to mail server for processing
There are also regulations that should prevent clients from puling the emails off of the central server and storing them on the PC itself, in the form of a pst file, as used with Outlook.
If the emails indeed were on Lerner's PC and not on the server, then the IRS is in direct violation of gov't regulations
There are also the regulation of email backups. IRS had contracted the company Sonasoft to backup emails. They cancelled this contract just weeks after Lerner's computer crashed.
Then there's also the issue of Sarbanes Oxley compliance. Apparently, the IRS is not subject to the same compliance laws as are imposed on publicly traded companies, the very companies the IRS collects taxes from. that is a$$ backwards.
Lastly, you must physically destroy a hard drive to prevent someone from retrieving data on a hard drive or perform a low-level format that actually writes 1/0's to every sector/block on a hard drive. A hard drive crash can simply mean part of the tables that allow the computer to know where the data is at was corrupted, but that does not mean the data is lost. it is 99.9% of the time, still there on the disk platters.
This entire issue wreaks of corruption and collusion