: new_message_id( fqdn = Socket.gethostname ) -> String
    fqdn: String

    å ID ֤ޤ
     fqdn ά줿ϥۥȤ̾Ȥޤ
     fqdn ꤹϥ륢åפǤʤɤλˤ
    ۥȤ̾ѤɬפΤȤߤʤ '.tmail' 
    ĤɥᥤѤޤϡʪΡץɥᥤǺ
    å ID Ȥνʣ򤱤뤿Ǥ

