What happens if the sender's Google account ceases to exist for whatever reason? What if Google ceases to exist?
I know that there are a lot of HIPAA "secure email" solutions that also do this, but I don't want this to become more common practice then it already is...
IMO those are different use cases. If that sender or Google itself were to disappear, hopefully the messages would just disappear too. It's better that they become inaccessible rather than public.
Long term archival is a different use case altogether, especially of encrypted materials. It's questionable whether any provider or medium can survive over the long term, so it's better to use an encryption system where you hold the keys and the encrypted data can be migrated to any sort of storage or provider over the years.
Keep HARs from the browser if you need your own record of the messages. Next step would be to determine how to extract the messages from a history of HARs and inject into your own mailbox or other storage system for archiving and search. Perhaps a browser extension to automate this automated logging of message retrieval.
Doesn’t matter. If using this and I send you an email, and my account disappears, you can no longer read the email you received because it’s merely a link to read something from my account on Google.
I know that there are a lot of HIPAA "secure email" solutions that also do this, but I don't want this to become more common practice then it already is...