When considering the cost of roofing materials, many people take into account just the shingle prices. This is incorrect, as a roof made just of roofing shingles will not work. You also need to consider all the accessories that are included in a complete roof system.
Business letters tend to have both the sender and receiver's address and the date at the top of the page and they begin with a polite salutation, such as dear Mr. and Mrs, followed by a blank line before the body or the content of the letter.
Those naming and designing this email feature probably had the real world counterpart to email in mind: letters. 1  Carbon copy paper made it possible to send the same letter to two (or even more if you hit the keys really hard) different people without the onerous task of having to write or type it twice.