I have a Windows Application that fills a grid on a form getting the
read/unread items from the installed Outlook application. I am using VS 2005
and the Outlook reference is ver 11.00 object model. This form supports
Outlook versions 2000 +

All versions except 2000 are working fine. The error we get is:

System.MissingMemberException: Public member 'SenderEmailType' on type
'MailItem' not found. etc....

This had been working for Outlook 2000 + (thanks very much to Dmitry) then I
had changed it slightly, got busy for a couple of months and now it seems to
be broken. We obviously don't have many customers using Outlook2000 :) .

Here is the code:

  Dim oApp As Object = CreateObject("Outlook.Application")
           If oApp Is Nothing Then
               MessageBox.Show("To utilize Email Inbox, it is required that
MS Outlook be installed on your computer.", "Email Inbox",
MessageBoxButtons.OK, MessageBoxIcon.Error)
               Exit Try
           End If

           Dim sClassComp As Object = "IPM.Note"
           Dim clsReadRe As Object = "REPORT.IPM.Note.IPNRN" ' this is the
class of a read receipt
           Dim clsDeliveredRe As Object = "REPORT.IPM.Note.DR" ' this is
the class of  delivery receipt
           Dim oNS As Outlook.NameSpace = oApp.GetNamespace("MAPI")
           Dim oInbox As Outlook.MAPIFolder =
oNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox)
           Dim oItems As Outlook.Items = oInbox.Items

           If Not chkAllItems.Checked Then
               oItems = oItems.Restrict("[Unread] = true")
           End If

           Dim oMsg As Object
           For i As Integer = 1 To oItems.Count
               getExchange = False
               oMsg = oItems.Item(i)

                 Select Case oMsg.MessageClass.ToString.ToUpper
                   Case "IPM.NOTE" 'email message

                       If Not (oMsg.Subject Is Nothing And oMsg.To Is
Nothing And oMsg.SenderName Is Nothing) Then

                           Dim strFrom As String = ""
                           drTemp = dtInBox.NewRow

                           If oMsg.SenderEmailType = "EX" Then
                               strFrom = oMsg.SenderName
                               getExchange = True

                           Else
                               strFrom = oMsg.SenderName & " " &
oMsg.SenderEmailAddress
                           End If

                           drTemp.Item("Subject") = oMsg.Subject
                           drTemp.Item("From") = strFrom
                           drTemp.Item("TimeReceived") = oMsg.ReceivedTime
                           drTemp.Item("Body") = oMsg.Body
                           drTemp.Item("To") = oMsg.To
                           drTemp.Item("CC") = oMsg.CC
                           drTemp.Item("EntryID") = oMsg.EntryID
                           drTemp.Item("StoreID") = oMsg.Parent.StoreID
                           drTemp.Item("EX") = getExchange

                           If oMsg.Attachments.Count > 0 Then
                               drTemp.Item("Attachments") = 1
                           Else
                               drTemp.Item("Attachments") = 0
                           End If

                           dtInBox.Rows.Add(drTemp)
                       End If

                   Case "REPORT.IPM.NOTE.DR" 'delivery notice
                       Dim strHappy As String
                       strHappy = ""

                   Case "REPORT.IPM.NOTE.IPNRN" 'read receipt
                       Dim strHappy As String
                       strHappy = ""

               End Select

           Next

The main question is why am I now getting an error when I check for the
SenderEmailType?