string filter;
if (outlook.Session.DefaultStore.IsInstantSearchEnabled) {
  filter =
    @"@SQL=(((""http://schemas.microsoft.com/mapi/proptag/0x001a001e"""
    + "CI_STARTSWITH 'IPM.Note')"
    + @" AND (""urn:schemas:httpmail:subject"" CI_STARTSWITH 'RE:'))"
    + @" AND (""urn:schemas:httpmail:datereceived"" >= '"
    + (DateTime.Now.ToUniversalTime() 
    - new TimeSpan(30, 0, 0, 0)).ToString("g") + @"'))";
}
else {
  filter =
    @"@SQL=(((""http://schemas.microsoft.com/mapi/proptag/0x001a001e"""
    + "LIKE 'IPM.Note%')"
    + @" AND (""urn:schemas:httpmail:subject"" LIKE 'RE:%'))"
    + @" AND (""urn:schemas:httpmail:datereceived"" >= '"
    + (DateTime.Now.ToUniversalTime() 
    - new TimeSpan(30, 0, 0, 0)).ToString("g") + @"'))";
}

Outlook.Items folderItems = folder.Items;
Outlook.Items filteredItems = folderItems.Restrict(filter);
StringBuilder builder = new StringBuilder();

foreach (Outlook.MailItem item in filteredItems) {
  builder.AppendLine(String.Format("{0},{1},{2}",
    item.SentOn, item.ReceivedTime, item.Size));
}

CalculateElapsedTime(builder.ToString());

public static void SaveAs(this Document doc) {
  SaveAs(doc, (string) null);
}

public static void SaveAs(this Document doc, string fileName) {
  SaveAs(doc, fileName, null);
}

public static void SaveAs(this Document doc, string fileName,
   WdSaveFormat? fileFormat) {
  SaveAs(doc, new DocumentSaveAsArgs { 
    FileName = fileName, FileFormat = fileFormat });
}

public static void SaveAs(this Document doc, DocumentSaveAsArgs args) {
  doc.SaveAs(
    ref args.FileNameInternal,
    ref args.FileFormatInternal,
    ref args.LockCommentsInternal,
    ref args.PasswordInternal,
    ref args.AddToRecentFilesInternal,
    ref args.WritePasswordInternal,
    ref args.ReadOnlyRecommendedInternal,
    ref args.EmbedTrueTypeFontsInternal,
    ref args.SaveNativePictureFormatInternal,
    ref args.SaveFormsDataInternal,
    ref args.SaveAsAOCELetterInternal,
    ref args.EncodingInternal,
    ref args.InsertLineBreaksInternal,
    ref args.AllowSubstitutionsInternal,
    ref args.LineEndingInternal,
    ref args.AddBiDiMarksInternal);
}

public static class RangeExtensions {
  public static Excel.Range Offset(
    this Excel.Range cells, int rowOffset, int columnOffset) {
    return cells.get_Offset(rowOffset, columnOffset) as Excel.Range;
  }
}

public static class ShapesExtensions {
  public static Excel.Shape AddChart(
    this Excel.Shapes shapes, Excel.XlChartType chartType) {
    return shapes.AddChart(chartType, 
      Type.Missing, Type.Missing, Type.Missing, Type.Missing);
  }
}

public static class ShapeExtensions {
  public static void Select(this Excel.Shape shape) {
    shape.Select(Type.Missing);
  }
}

public static class ChartExtensions {
  public static void SetSourceData(this Excel.Chart chart, 
    Excel.Range range) {
    chart.SetSourceData(range, Type.Missing);
  }
}

// Provide a logging class for our LINQ-to-DASL queries.
internal class DebuggerWriter : TextWriter {
  public override Encoding Encoding {
    get { throw new NotImplementedException(); }
  }

  public override void WriteLine(string value) {
    Debug.WriteLine(value);
  }
}

// Subclass the extensions Mail class so that we can expose a Size
// property that maps to the real Outlook size property.
internal class MailEx : Mail {
  [OutlookItemProperty("http://schemas.microsoft.com/mapi/proptag/0x0E080003")]
  public int Size { get { return Item.Size; } }
}

// Create the ItemsSource manually (this is
// what Items.AsQueryable() does implicitly).
var source = new ItemsSource<MailEx>(folder.Items);

// Set the Log property of the ItemsSource to a TextWriter.
// It will be given the DASL query string immediately before 
// the query is executed in Outlook.
source.Log = new DebuggerWriter();

//var filteredItems = (from item in folder.Items.AsQueryable<Mail>()
var filteredItems = (from item in source
                     where item.MessageClass.StartsWith("IPM.Note")
                     && item.Subject.StartsWith("RE:")
                     && item.DateReceived >= 
                     DateTime.Now.ToUniversalTime() -                        new TimeSpan(30, 0, 0, 0)
                     select item).ToList();

//foreach (Mail item in filteredItems)
foreach (MailEx item in filteredItems) {
  builder.AppendLine(String.Format("{0},{1},{2}",
    //item.Date, item.DateReceived, item.Body.Length));
    item.Date, item.DateReceived, item.Size));
}

//Outlook.Items folderItems = folder.Items;
//Outlook.Items filteredItems = folderItems.Restrict(filter);
//foreach (Outlook.MailItem item in filteredItems) {
//  builder.AppendLine(String.Format("{0},{1},{2}",
//    item.SentOn, item.ReceivedTime, item.Size));
//}

// Get a table of mail items, remove the default column set, 
// and add the specific columns we're interested in instead.
table = folder.GetTable(filter, Outlook.OlTableContents.olUserItems);
table.Columns.RemoveAll();
table.Columns.Add("SentOn");
table.Columns.Add("ReceivedTime");
table.Columns.Add("Size");

// Iterate the table rows.
while (!table.EndOfTable) {
  Outlook.Row nextRow = table.GetNextRow();
  builder.AppendLine(String.Format("{0},{1},{2}",
    nextRow["SentOn"], nextRow["ReceivedTime"], nextRow["Size"]));
}

Dim source As New ItemsSource(Of MailEx)(folder.Items)
Dim builder As New StringBuilder()

Dim filteredItems = ( _
  From item In source _
  Where item.MessageClass.StartsWith("IPM.Note") _
  AndAlso item.Subject.StartsWith("RE:") _
  AndAlso item.DateReceived >= _
  (DateTime.Now.ToUniversalTime() - New TimeSpan(30, 0, 0, 0)) _
  Select item).ToList()

For Each filteredItem In filteredItems
  builder.AppendLine(String.Format("{0},{1},{2}", _
  filteredItem.Date, filteredItem.DateReceived, filteredItem.Size))
Next
MessageBox.Show(builder.ToString())

Friend Class MailEx
  Inherits Mail

  <OutlookItemProperty(     "http://schemas.microsoft.com/mapi/proptag/0x0E080003")> _
  Public ReadOnly Property Size() As Integer
    Get
      Return MyBase.Item.Size
    End Get
  End Property

  <OutlookItemProperty(     "http://schemas.microsoft.com/mapi/proptag/0x001a001e")> _
  Public Overrides ReadOnly Property MessageClass() As String
    Get
      Return MyBase.Item.MessageClass
    End Get
  End Property
End Class