* @param to_str "To:" header, or NULL
* @param cc_str "Cc:" header, or NULL
* @param bcc_str "Bcc:" header, or NULL
* @param subject_str Subject of the message, or NULL
* @param body_str Body of the message (without signature), or NULL
* @param to_str "To:" header, or NULL
* @param cc_str "Cc:" header, or NULL
* @param bcc_str "Bcc:" header, or NULL
* @param subject_str Subject of the message, or NULL
* @param body_str Body of the message (without signature), or NULL