If your mail server supports it you can forward the headers (or the entire email) on to several further addresses. Really need more detail about the mail server and the mail client you are using.
Generally, once a mail has been read the mail server stores that information and so it will appear to anyone else looking in that mailbox that the email has been attended to. You can set Outlook to NOT automatically mark emails as read (Options>>Read>>untick first checkbox), but I don't think that this is what you are really after.