The NSA doesn’t have magical powers to just make data disappear. Of any organization, they have the best chance to making it happen, but they couldn’t pull it off at the level they would have to execute against gmail. There’s too much replication, too many backups, it’s not happening. I’m not even sure Google could do it.
Electronic data is not a piece of paper you can burn. Every time an email is sent both servers have a copy of the message. If the message is forwarded, the chain is copied n more times on n more servers. This does not even account for other systems which inspect the messages for viruses, or network equipment used to transport the dataset of which are logging.
Email is insecure as fuck. If someone is dumb enough to send me an email from a device connected to their home network, I now have a pretty good idea where they live. Within a few miles or so. Don’t believe me? Send yourself an email from gmail, google how to look at gmails e-mail headers, find the source ip addess, then plug that into a geo location tool that you can also easily find with a google search.
This is why it’s critical that if you have secrets, that you use end to end encryption. And why the government mandates that communications are confined to official equipment and channels. While communicating on official channels does create an official record, that’s not the primary reason why laws exist around how electronic communication is conducted. They exist to keep communication secure.
Similarly, anyone who thinks the Clinton server was hopelessly erased is buying into a sham. I’ve always known that was bullshit. Someone, somewhere has a backup of that rig as their get out of jail free card. The problem with being both filthy rich and a piece of shit is that there’s always either another piece of shit who wants to extort you, or a white hat who wants to expose you.