What I would find lovely is to connect my already existing Thunderbird profile that exists locally. I have 5 email accounts connected and there is no real need to sync them twice on the same machine.
That is a neat idea. We could tap into the locally-synced Thunderbird files for the knowledge graph, which would make ingestion straightforward. We could explore this. The write side - pre-creating drafts on threads, sending etc. still needs the provider work that made us defer IMAP for all email handling.