But can it explain how a financial institution can reliably send me a 2FA passcode in a few seconds via email, but a message from wife in the other room can take a couple of hours to arrive?
Presumably because the financial institution sends the email directly to your email provider via SMTP while your wife sends the email to her email provider via a mail client protocol like POP3 or IMAP, and then her email provider forwards the email on to your email provider via SMTP at its leisure
Does anyone actually implement the BURL extension to IMAP? I think pretty much all mail clients just use SMTP for submission.
Not a bad guess, except that gmail is the email provider for both my wife and myself.
Then the answer might be that the bank does not use Gmail. It is after all known to be not that great.
Gmail doesn’t send instantly. This is why they could add the undo feature for sending emails.
That explains a ten second delay, not a couple of hours as parent poster claims.