My hope is that, depending on the service they're tendering, plaintext (or at least static) emails will become a legal requirement. What if you need to read a

My hope is that, depending on the service they're tendering, plaintext (or at least static) emails will become a legal requirement. What if you need to read a "dynamic" email a few years after it was sent, and the company rendering the dynamic components goes away? And those dynamic components are somehow essential to the content of the email? A receipt, for example. There's some precedent for this kind of regulation. For example, the government requires medicare advantage insurance carriers to send physical mail to insured members under many circumstances, regardless of the member's digital-accessibility constraints or lack thereof.