Goldman Sachs is suing Google to un-send an accidental email

What if the person who they had accidentally sent the e-mail to hadn't been a Gmail user but had instead downloaded the message to Outlook on their home PC. Would GS think they could get a court order to search that person's home to retrieve all copies of the message that they might have on their hard drive and backups?

For that matter, how do they know that the Gmail user hasn't already downloaded a copy of the message and sent it to somebody? (Most probably, they just deleted it, since it was worthless to them.)

What you're describing may not be too far fetched: recall Apple's lost iPhone 5 prototype incident[1].

1 - http://www.ibtimes.com/sf-police-allow-apple-agents-search-p...

So if I send a letter to the wrong person I should be able to sue the postal service to remove the letter from the recipients mailbox?

Seems like something that could create a really dangerous precedent. Not exactly something you want in a common law country.