Just a short comment on the proposed UI for Netscape 6 S/MIME. When composing a message and the intention is to encrypt the message, I prefer the feeback of the certificate icon next to each recipient's name/address versus the toolbar status. It seems to track easier by keeping the information lumped together rather than having to scan all over the UI to determine what is happening.
Instead of a "certificate" icon how about using a "lock" icon instead? A lock seems to indicate the intention of security more than a blue-ribbon symbol. I also think it indicates more of an intention than a blue-ribbon symbol which I think implies possession; it means "you have the recipients certificate" which may not be the case if you've never corresponded with them before and will get their encryption cert from a directory server. Users don't have to know that they have to have a user's certificate in order to send them encrypted email...they just want to send them an encrypted message and the program's supposed to take care of everything else. I anticipate that as you are addressing or composing your message the applicaiton is scanning your addressbook and certificate database, along with the directory servers to retrieve the recipients' encryption certificates. If there are no valid encryption certificates available for a particular recipient, the lock icon by the affected recipient should be replaced with something to indicate a problem, like a lock icon with a slash through it, an exclamation icon or a lock with a yellow "yield" type of icon in it. If the user doesn't notice these and tries to send the message anyhow, an error dialog will prompt the user about the condition and ask them what to do. I like the padlock-Send icon to indicate if the user's encryption/signing intentions can be carried out. I think more users will notice the "Send" icon changing state more so than a status bar icon. But I think there is a very minor distinction between an unlocked and locked padlock; see other comments above on other possibilities. tooltips/mouse-overs: Further, if the user mouses over such an icon that represents "can't get the user's encrpytion certificate", the tooltip should indicate what this means. Like "you cannot send this user an encrypted message, click for more information". If they user clicks on that icon, the security info window would pop up and tell the user that "the recipient needs to get an email encryption certificate in order to send them encrypted email". (obviously it would be something less geeky) I'd also like to see tooltip mouseovers for the "send" icon that says things like "this email will be signed/encrypted when sent" if there is a lock icon on it. And "this email CANNOT be signed/encrypted" if there is a "yield+lock" icon on the Send button if the user intended to send a secure message. cert selection: instead of the "select..." button, how about a pop-down menu picker with the choices being the user's encryption/signing certificates (as appropriate for) and the final options being "Restore/Manage certificates...." and "Get a new certificate...". For users with multiple certificates, this will reduce the number of clicks to choose their certificate. If a user doesn't have any certificates at all, the menu choices should be "Get a new certificate..." and "Restore/Manage your certificates..."
