a pretty stupid Mail.app IMAP bug hoses Fastmail:
Yes you read that right. It’s copying all the email from the Junk Folder back into the Junk Folder again!. This is legal IMAP, so our server proceeds to create a new copy of each message in the folder. It then expunges the old copies of the messages, but it’s happening so often that the current UID on that folder is up to over 3 million. It was just over 2 million a few days ago when I first emailed the user to alert them to the situation, so it’s grown by another million since. The only way I can think this escaped QA was that they used a server which (like gmail) automatically suppresses duplicates for all their testing, because this is a massively bad problem.
One of those analyses showed that when a human was behind the wheel, Google’s cars accelerated and braked significantly more sharply than they did when piloting themselves. Another showed that the cars’ software was much better at maintaining a safe distance from the vehicle ahead than the human drivers were. “We’re spending less time in near-collision states,” said Urmson. “Our car is driving more smoothly and more safely than our trained professional drivers.”