I am in the process of switching IMAP providers because the one I have been using for the last ~10 years, FastMail, decided to jack up the price and I could barely justify the old price. Furthermore, I want to get my own family on to private/custom email and it would be absurd to pay FastMail’s price 5x. Anyways… so how to best move the 70k emails from FastMail to my new provider?