public static void Control()
        {
            ReservationsEntities3 Db = new ReservationsEntities3();
            List <int>            ReservationIDList = Db.Reservations.Select(x => x.ReservationID).ToList();
            List <string>         MailList          = new List <string>();
            List <int>            RoomID            = new List <int>();
            List <string>         Time = new List <string>();

            foreach (var item in ReservationIDList)
            {
                if (DateTime.Today.Date.AddDays(1) == Convert.ToDateTime(Db.Reservations.Where(x => x.ReservationID == item).Select(x => x.Date.Value)))
                {
                    MailList = Db.Participants.Where(x => x.ReservationID == item).Select(x => x.MailAdress).ToList();
                    Time     = Db.Reservations.Where(x => x.ReservationID == item).Select(x => x.StartTime).ToList();
                    RoomID   = Db.Reservations.Where(x => x.ReservationID == item).Select(x => x.MeetingRoomID).ToList();
                    MailProcedure.SendMail(MailList, RoomID[0], Time[0]);
                }
            }
        }