I get it, you've got to update SMTP, the mail client, and likely other points (mail storage). But that's no reason not to try. Look at DKIM and SPF--we've maid steps to protect against forgeries.
I'm not advocating either way, I'm just saying that it's a problem with a higher barrier to clear since it requires far more buy-in to be meaningfully implemented. You can go and encrypt your email right now but unless you get an organisation with an incredible degree of power to back you you'll be sending messages most people can't read and recieving unencrypted stuff in return.
I get it, you've got to update SMTP, the mail client, and likely other points (mail storage). But that's no reason not to try. Look at DKIM and SPF--we've maid steps to protect against forgeries.