Messages sent to a Mail address were refused, and returned to the sender, when they had no Reply-To header, which most messages do not. They are now received. A message refused before this fix was not stored; ask its sender to send it again.
A message's sent time is now stored in UTC, so it shows at the right time whatever the sender's time zone. If storing a message fails unexpectedly, the mail server now keeps it and tries again instead of returning it to the sender.