Marco seems really interesting! I'm curious as to how the UX is with solely IMAP. Whenever I use iCloud/Outlook/Gmail accounts on a different email client (e.g., using my Outlook email on Mail.app or my Gmail on the Outlook client), the IMAP experience just feels subpar compared to using the regular client (I have three email clients on my dock right now because of this...). Usually this shows in not great push notifications or actions I perform not getting synced properly. Has Marco been dealing with these issues, or have I just not been using the right email clients?
Example of the kind of behavior that I've come to expect with using megacorp mail over IMAP: https://youtu.be/02NtiPes5IM?t=319