SMPTS is a thing and IMAPS are a thing too.
New Rules (proposals of laws that will fix problems)
Inspired by Bill Maher’s “New Rules” segment of his show, but not as satire. Some satire is perhaps welcome but this is like a serious bug tracker for the real world (not bugs in software apps).
Those are not end to end protocols. So every email host along the path sees where you bank, and the ISPs of the services of those hosts.
Also if you run your own mail server, any eavesdropper outside those tunnels would learn where you bank without seeing the payload, just seeing traffic go from A to B. That’s less likely though. The main problem is email providers and ISPs being inherently the loop (particularly in the US after Trump reversed Obama’s requirement that ISPs obtain consent to collect and sell customer data, which Biden has not reversed back).
or just pass a law requiring all government post offices to provide low (or no cost) banking services to the entire population and empower them to issue loans for up to 2-3x your annual income at 3% interest.
It will gut bank's home loan business, making housing more affordable and skip the email question entirely.
A bank that simply holds an asset account (not a loan/liability account) is spamming ads to get car insurance from their partner, ID theft insurance, discounts at the vet, etc. It’s in fact the asset accounts that are sensitive. Debt collectors (and data brokers, by extension) want to know where your money is stashed, not who you owe money to. That’s also the account that’s sensitive to various attacks.
BTW, the bank bailout in the US around 2008 exceeded 10 years of NASA’s running budget. That’s how attached one federal gov was to their private banks, who tend to feed the right wing republican campaigns quite well (yet that bailout was under Obama). Taking those banks down is really well into the realm of fiction fantasy.
There is no denying government finance (soft corruption) from financial institutions but what you are suggesting is quite easy for any institution to bypass with bulk paperwork; unless you refine it to be in an exact form with no other subjects and for which the optional nature must be explicitly stated with clear terms. But then banks can just say no interest on accounts unless you agree and boom the problem returns.