Try Dim NS As Microsoft.Office.Interop.Outlook.NameSpace Dim myOlApp As Microsoft.Office.Interop.Outlook.Application=New Microsoft.Office.Interop.Outlook.ApplicationClass Dim objOwner As Microsoft.Office.Interop.Outlook.Recipient Dim EntryID As String Dim SchemaTransportHeader As String = "http://schemas.microsoft.com/mapi/proptag/0x007D001E" Dim SchemaMessageIDHeader As String = "http://schemas.microsoft.com/mapi/proptag/0x1035001F" Dim filter As String = "@SQL=" & Chr(34) & SchemaMessageIDHeader & Chr(34) & "='" & MessageID & "'" NS=myOlApp.GetNamespace("MAPI") objOwner=NS.CreateRecipient(Mailbox) objOwner.Resolve Dim tbl As Microsoft.Office.Interop.Outlook.Table If SubFolderEmail Then tbl = myOlApp.Session.GetSharedDefaultFolder(objOwner,Microsoft.Office.Interop.Outlook.OlDefaultFolders.olFolderInbox).Folders(FolderName).GetTable(filter, Microsoft.Office.Interop.Outlook.OlTableContents.olUserItems) Else tbl = myOlApp.Session.GetSharedDefaultFolder(objOwner,Microsoft.Office.Interop.Outlook.OlDefaultFolders.olFolderInbox).GetTable(filter, Microsoft.Office.Interop.Outlook.OlTableContents.olUserItems) End If Dim oRow As Microsoft.Office.Interop.Outlook.Row = tbl.GetNextRow() EntryID = oRow("EntryID").ToString() Dim oMail As Microsoft.Office.Interop.Outlook.MailItem Dim oMeeting As Microsoft.Office.Interop.Outlook.MeetingItem Dim oPA As Microsoft.Office.Interop.Outlook.PropertyAccessor Try oMail= CType(myOlApp.Session.GetItemFromID(EntryID), Microsoft.Office.Interop.Outlook.MailItem) 'Obtain an instance Of PropertyAccessor Class. oPA= oMail.PropertyAccessor Transport = CType(oPA.GetProperty(SchemaTransportHeader), String) Catch Try oMeeting= CType(myOlApp.Session.GetItemFromID(EntryID), Microsoft.Office.Interop.Outlook.MeetingItem) 'Obtain an instance of PropertyAccessor class. oPA= oMeeting.PropertyAccessor Transport = CType(oPA.GetProperty(SchemaTransportHeader), String) Catch e As System.Exception Excptn=e.ToString End Try End Try Catch e As System.Exception Excptn=e.ToString End Try