Function encrypt_message 

pub fn encrypt_message(
    cfg: &Pgp,
    recipients: &[String],
    sign: bool,
    text: &str,
    flowed: bool,
) -> Result<String>

Wrap a finalized draft in multipart/encrypted for recipients (which the caller assembles from To/Cc/Bcc plus the sender, so the author can read their own mail); sign adds a signature inside the encryption layer. Headers, including Subject, stay in clear.