I love the new Mail, but I have to say that one thing annoys me in particular. There is no way to set Mail to display all recipients of a message by default. Each time you want to see whether there are other recipients in a message, you have to click on details for each particular message. If you don't click on details and just blindly reply to a message, Mail does not warn or ask you whether you want to reply to all. So not just in theory but in a relatively normal situation, you could receive a message and read/reply/forward/delete having absolutely NO idea that it had other recipients. The only way to actually know is for you to manually click for the details. There is absolutely no other indication. Also, there is the ability for you to ask mail to indicate whether you were a primary recipient or a copied recipient in the "Show TO/CC" setting, but that doesn't help because if someone sends a message that is addressed to you but has other recipients copied, once again, you will not have a clue.