After upgrading to this new version my group lists again started developing errors with a message that says something like An error occurred while sending mail. "The mail server responded: 5.5.0 <list name > invalid address. Please check the message recipient and try again." If I again resend the messages with everything the same (because the list is correct as is) the addressing it goes through on the second try. I have remade the lists but it does not fix the problem this was a big problem for me a number of upgrades before and then I had to go back to a older version. But it was fixed in a subsequent upgrade