>A daemon that pulls new mail from my IMAP servers to my local maildir as soon as it arrives. (I know mutt has an IMAP mode, and it looks like that's aerc's primary mode of operation, too, but I like to have a local copy of my entire mail archive.)
What's wrong with fetchmail? Granted, it's not "as soon as it arrives", but you can run it every minute if you want.
Well, you can't log in until you recieve the email.
I've had a variant of this due to using a custom domain with a small email provider that was either slow or greylisting; the second-factor login email for GOG took longer than 15 minutes to arrive, by which time it had expired. I had to keep trying until it came through quickly enough.
What's wrong with fetchmail? Granted, it's not "as soon as it arrives", but you can run it every minute if you want.