I understand that using encryption for email isn't particularly mainstream (a fraction of a percentage of users, at a guess). Is that the only reason that banks and other sensitive companies do not offer some kind of encryption for email notifications?
For example, my bank sends me an email every month:
Subject: Your monthly statement is ready
Your monthly statement is ready. Please sign in to the bank's website to download it.
For security (i.e. to prove this really came from us), your postcode is S12 TYX.
While admittedly it's not a huge deal, I'd rather Google - or any mail server - didn't ever receive my postcode in plaintext. This also applies to, for example, receipts from PayPal.
Technically, I would think it fairly trivial for the bank to encrypt this notification using my public key. Is there anything I've overlooked in coming to that conclusion?