> maybe Amazon will helpfully add an alert to your order receipt when the shipment is unexpectedly delayed?

Alternatively Amazon could send a followup email. This way the sequence of events is preserved and not dependent on the sender.

I currently use email as a immutable list of events that have occurred in my life but with this I can no longer continue to do so.

So just use a client that doesn't support dynamic email, or disable the feature in clients that do.

> At any rate, the other MIME parts aren't gone. In gmail you can just click "show HTML message"

If dynamically loaded content becomes widely supported, why would that mime part continue to exist? The web already doesn’t work without javascript. Why wouldn’t email quickly follow suit as well?

MUAs have widely supported HTML emails for decades, and yet Amazon still includes a text/plain part with their order confirmation emails.