private static void WriteMessage(Message mes, SqlConnection connection) { string cmdString = "SELECT A.USERNAME FROM DialogueUser A INNER JOIN AccountSettings B ON A.USERNAME = B.USERNAME WHERE A.ROOM_ID = @id AND B.MAIL_MESSAGES_ENABLED = 1"; SqlDataAdapter da = new SqlDataAdapter(cmdString, connection); da.SelectCommand.Parameters.AddWithValue("@id", mes.RoomId); DataSet set = new DataSet(); da.Fill(set); List <string> users = new List <string>(); foreach (DataRow row in set.Tables[0].Rows) { string user = row["USERNAME"].ToString(); users.Add(user); } foreach (string user in users) { if (!NotificationHub.IsOnline(user)) { Dictionary <string, string> toPass = new Dictionary <string, string>(); toPass.Add("username", user); toPass.Add("dialogue_id", mes.RoomId.ToString()); MailManager.SendMessage(toPass, MailType.MESSAGE); } } }