There are three different outgoing address fields in any email application, To:, Cc: and Bcc:. When should you use each? Easy. If you are mailing within a group and want all addressed equally, use To:. If you are mailing one person, say the head of a committee, and want others in the group to be aware of it, the main address goes in the To: field and the rest in Cc: (carbon copy). If you are mailing to an unrelated group, say passing a cartoon or joke to a bunch of friends, PLEASE, please, please, use the Bcc: field. It will hide the other names from each recipient.
If you forward something to others, PLEASE, please, please, clean up the message before you send it off. Strip out all of the header info, all of the prior recipients addresses, all the comments, before hitting the Send button. At the same time, if you are using Mail, you can also highlight the entire message, then go up to the Format menu and select Quote Level > Decrease to eliminate all of the forwarding indents. In Entourage, use the Edit > Auto Text Cleanup > Remove Quoting to accomplish the same thing. Using a different mail app? Check the formatting menus. They may call it something else, but the editing ability is there.