public static DataSet convertDataReaderToDataSet(DbDataReader reader)
{
    DataSet dataSet = new DataSet();
    do
    {
        // Create new data table
        DataTable schemaTable = reader.GetSchemaTable();
        DataTable dataTable = new DataTable();

        if (schemaTable != null)
        {
            // A query returning records was executed
            for (int i = 0; i < schemaTable.Rows.Count; i++)
            {
                DataRow dataRow = schemaTable.Rows[i];
                // Create a column name that is unique in the data table
                string columnName = (string)dataRow["ColumnName"];
                // Add the column definition to the data table
                DataColumn column = new DataColumn(columnName, (Type)dataRow["DataType"]);
                dataTable.Columns.Add(column);
            }
            dataSet.Tables.Add(dataTable);
            // Fill the data table we just created
            while (reader.Read())
            {
                DataRow dataRow = dataTable.NewRow();

                for (int i = 0; i < reader.FieldCount; i++)
                    dataRow[i] = reader.GetValue(i);

                dataTable.Rows.Add(dataRow);
            }
        }
        else
        {
            // No records were returned
            DataColumn column = new DataColumn("RowsAffected");
            dataTable.Columns.Add(column);
            dataSet.Tables.Add(dataTable);
            DataRow dataRow = dataTable.NewRow();
            dataRow[0] = reader.RecordsAffected;
            dataTable.Rows.Add(dataRow);
        }
    }
    while (reader.NextResult());
    return dataSet;
}

public bool IsMailValid(string emailAddress)
{
    StringBuilder sb = new StringBuilder();
    sb.Append(@"^(([^<>()[\]\\.,;:\s@\""]+");
    sb.Append(@"(\.[^<>()[\]\\.,;:\s@\""]+)*)|(\"".+\""))@");
    sb.Append(@"((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}");
    sb.Append(@"\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+");
    sb.Append(@"[a-zA-Z]{2,}))$");
    Regex reStrict = new Regex(sb.ToString());
    bool isStrictMatch = reStrict.IsMatch(emailAddress);
    return isStrictMatch;
}

Page.Form.DefaultButton = btn1.ClientID;

Page.Form.DefaultFocus = tb1.ClientID;