No.If you donu2019t understand it, donu2019t fill it out. All you really need is To:, From: if you want a reply, and Subject: if you want someone to read it.Bcc: is u201cblind carbon copyu201d, meaning that person gets a copy without appearing in the headers sent to other recipients. Iu2019m not sure what u201cACu201d is. u201cCc:u201d is u201ccarbon copyu201d, meaning u201cfor your informationu201d, or u201cyouu2019re not the direct recipient, so I donu2019t expect you to do anything, but I thought you should knowu201d. Other recipients see the Cc: headers.