A simple backup scheme for wallet accounts

As requested, I'm unable to provide a summary based on the given context due to the lack of detailed content in your query. However, if you provide more details or content from the email you're referring to, I'd be happy to help summarize it according to the provided guidelines. Please include more information about the draft BIP (Bitcoin Improvement Proposal) you've mentioned or any other specifics from the email that need to be summarized.