In US Forensic Expert: UK Defendant Convicted with NSA Email Sweep, internet security expert witness writes:
The American spy agency, NSA, secretly surveilled a Yahoo! mail account belonging to co-defendants of UK prisoner, Russell Knaggs, in connection with an alleged complex drug conspiracy. The users of the account were employing a draft email in the Yahoo! account as a messaging board – deleting, editing, and rewriting drafts, but never actually sending an email. Said interceptions occurred continuously over several months, even while draft emails were in the process of being edited .
California forensic expert, Steve Burgess, analyzed evidence presented by the UK authorities and showed that captures of email drafts in the account were intercepted ongoingly, and that at times multiple copies of a draft only minutes apart were intercepted, even as the author was typing.
Yahoo! officers in the UK and US said that such capabilities did not exist – that any deleted draft email data older than 48 hours that was unavailable to the user of the account was also unavailable to Yahoo! – that it was rendered impossible to recover.