This is super clever, and I hope this takes off.
At the same time, I have to worry: SMTP is forever, but I'm not so sure that IMAP is forever.
Email is increasingly becoming a fragmented oligopoly, and the major players are promoting their own alternative protocols. IMAP is becoming a very optional legacy feature.
If the success of this project required additional integrations with EAS and Google's mail APIs, would you do the work or reject the idea on principle?