And they are for the well-defined accounting periods, e.g. monthly or quarterly, not some sort of ephemeral "rollup to time of download". That would drive me mad if they had different periods depending on download timing.
I can't know for certain, but my gut tells me they are just generating PDFs at the same time they perform the general reporting run that also leads to printed statements. And then they have some limited retention history to limit the storage costs.
Having to log in to a half-maintained, slow web portal with terrible UI that is down 25% of the time is a really terrible way to get your sensitive and often important documents.
But, a potential sender with important messages still needs do some pre-flight email verification over this path, e.g. sending a verification code encrypted the same way, to validate that the intended user can read it and send it back via another authenticated channel. This ensures that the sender-specific user identity actually possesses control of that email address and the discovered private key. It also reduces the impact of a malicious email provider to only denial-of-service rather than content interception.
So, is that discovery protocol worth it, versus just having an opt-in setting where the user supplies their desired public key and email address in the same form?
My personal tax agent only accepts forms and sends them back via email. I had a conversation with him about using password protected zips and he just told me he won't accept them.
My hospital sent me a PDF that I was to fill in and email back with cleartext credit card information filled in to pay bills. Screenshot:
https://infosec.exchange/@jsmall/116745959468132388
I recently deal with an inheritance and the Super Fund would only accept legal documents by email. I could go on, this is normal.