//R
//R/body.R
//R/mime.R
//R/utils.R
//R/header.R
//R/render.R
//R/server.R
//R/address.R
//R/options.R
//R/parties.R
//R/encoding.R
//R/envelope.R
//R/attachment.R
//R/header-mail.R
//R/header-mime.R
//R/header-expires.R
//R/header-language.R
//R/header-precedence.R
//R/header-sensitivity.R