B means Blind

Why on earth did my boss reply to a bcc email I sent? He was not supposed to. Now I look like a smug guy after scolding our partner's support team and BCCing him. Email client apps like Eudora or Outlook should have some special alert message box with a critical icon when you attempt to reply to a bcc email. It should have something like "You are in the BCC list dammit! Do you really wanna hit that Send button?"