Const PR_SECURITY_FLAGS = “http://schemas.microsoft.com/mapi/proptag/0x6E010003“

                Dim prop As Long = CLng(.PropertyAccessor.GetProperty(PR_SECURITY_FLAGS))
                Dim ulFlags As Object = 0


                '.PropertyAccessor.SetProperties(PR_SECURITY_FLAGS, 35)
                If encrypt Or electronicSign Then
                    If encrypt And electronicSign Then
                        ulFlags = ulFlags Or &H1 ' Add the encrypted flag
                        ulFlags = ulFlags Or &H2 ' Add the signed flag
                    ElseIf encrypt Then
                        ulFlags = ulFlags Or &H1 ' Add the encrypted flag
                    Else
                        ulFlags = ulFlags Or &H2 ' Add the signed flag
                    End If
                    .PropertyAccessor.SetProperty(PR_SECURITY_FLAGS, ulFlags)
                Else

                End If

Public Overloads Shared Function ExportToExcel(ByVal source As IEnumerable) As Excel.Application
        Return ExportToExcel(source, True)
    End Function
    Public Overloads Shared Function ExportToExcel(ByVal dt As System.Data.DataTable, ByVal worksheetName As String) As Excel.Application
        Return ExportToExcel(dt, worksheetName, False, True)
    End Function

    Public Overloads Shared Function ExportToExcel(ByVal source As IEnumerable, ByVal worksheetName As String) As Excel.Application
        Return ExportToExcel(source, worksheetName, True)
    End Function

    Public Overloads Shared Function ExportToExcel(ByVal dt As System.Data.DataTable, excelIsVisible As Boolean) As Excel.Application
        Return ExportToExcel(dt, Nothing, False, excelIsVisible)
    End Function
    Public Overloads Shared Function ExportToExcel(ByVal source As IEnumerable, excelIsVisible As Boolean) As Excel.Application
        Return ExportToExcel(source, Nothing, False, excelIsVisible)
    End Function
    Public Overloads Shared Function ExportToExcel(ByVal dt As System.Data.DataTable, ByVal worksheetName As String, ByVal saveAsFileNameWithPath As String) As Excel.Application
        Return ExportToExcel(dt, worksheetName, saveAsFileNameWithPath, True)
    End Function
    Public Overloads Shared Function ExportToExcel(ByVal source As IEnumerable, ByVal worksheetName As String, ByVal convertNumberStoredAsTextToNumbers As Boolean) As Excel.Application  ', ByVal outputPath As String)
        Return ExportToExcel(source, worksheetName, convertNumberStoredAsTextToNumbers, True)
    End Function
    Public Overloads Shared Function ExportToExcel(ByVal dt As System.Data.DataTable, ByVal worksheetName As String, ByVal saveAsFileNameWithPath As String, excelIsVisible As Boolean) As Excel.Application
        Return ExportToExcel(dt, worksheetName, saveAsFileNameWithPath, False, excelIsVisible)
    End Function

    Public Overloads Shared Function ExportToExcel(ByVal source As IEnumerable, ByVal worksheetName As String, ByVal saveAsFileNameWithPath As String) As Excel.Application
        Return ExportToExcel(source, worksheetName, saveAsFileNameWithPath, False, True)
    End Function
    Public Overloads Shared Function ExportToExcel(ByVal source As IEnumerable, ByVal worksheetName As String, ByVal saveAsFileNameWithPath As String, ByVal convertNumberStoredAsTextToNumbers As Boolean) As Excel.Application  ', ByVal outputPath As String)
        Return ExportToExcel(source, worksheetName, saveAsFileNameWithPath, convertNumberStoredAsTextToNumbers, True)
    End Function

    Public Overloads Shared Function ExportToExcel(ByVal dt As System.Data.DataTable, ByVal worksheetName As String, ByVal convertNumberStoredAsTextToNumbers As Boolean) As Excel.Application
        Return ExportToExcel(dt, worksheetName, convertNumberStoredAsTextToNumbers, True)
    End Function

    Public Overloads Shared Function ExportToExcel(ByVal dt As System.Data.DataTable, ByVal worksheetName As String, ByVal convertNumberStoredAsTextToNumbers As Boolean, excelIsVisible As Boolean) As Excel.Application
        Return ExportToExcel(dt, worksheetName, Nothing, convertNumberStoredAsTextToNumbers, excelIsVisible)
    End Function
    Public Overloads Shared Function ExportToExcel(ByVal source As IEnumerable, ByVal worksheetName As String, ByVal convertNumberStoredAsTextToNumbers As Boolean, excelIsVisible As Boolean) As Excel.Application  ', ByVal outputPath As String)
        Return ExportToExcel(source, worksheetName, Nothing, convertNumberStoredAsTextToNumbers, excelIsVisible)
    End Function

    Public Overloads Shared Function ExportToExcel(ByRef dt As System.Data.DataTable, ByVal worksheetName As String, ByVal saveAsFileNameWithPath As String, ByVal convertNumberStoredAsTextToNumbers As Boolean, ByVal excelIsVisible As Boolean) As Excel.Application  ', ByVal outputPath As String)

        Dim excelApp As Excel.Application = Nothing
        Dim excelWorkbook As Excel.Workbook
        Dim excelSheet As Excel.Worksheet
        Try
            excelApp = New Excel.Application()
            excelApp.Visible = False
            excelWorkbook = excelApp.Workbooks.Add(Type.Missing)
            If excelWorkbook.Worksheets Is Nothing OrElse excelWorkbook.Worksheets.Count = 0 Then
                excelWorkbook.Sheets.Add(Count:=1, Type:=Excel.XlSheetType.xlWorksheet)
            End If
            excelSheet = CType(excelWorkbook.Worksheets(1), Excel.Worksheet)

            Return ExportToExcel(dt, worksheetName, saveAsFileNameWithPath, convertNumberStoredAsTextToNumbers, excelIsVisible, excelSheet)
        Catch ex As Exception
            If excelApp IsNot Nothing Then excelApp.Visible = True
            Throw New Exception("Can't initialize Excel application. Error: " & ex.Message)
        Finally
            excelSheet = Nothing
            excelWorkbook = Nothing
            excelApp = Nothing
        End Try



    End Function

    Public Overloads Shared Function ExportToExcel(ByRef dt As System.Data.DataTable, ByVal worksheetName As String, ByVal saveAsFileNameWithPath As String, ByVal convertNumberStoredAsTextToNumbers As Boolean, ByVal excelIsVisible As Boolean, ByRef excelSheet As Excel.Worksheet) As Excel.Application  ', ByVal outputPath As String)
        If excelSheet Is Nothing Then
            Throw New ArgumentNullException("Excel Application or Excel Sheet arguement is NULL")
        End If

    Public Shared Function IsInEditMode(ByRef xlApp As Excel.Application) As Boolean

        If xlApp.Interactive = False Then
            Return False
        Else
            Try
                xlApp.Interactive = False
                xlApp.Interactive = True

                Return False
            Catch
                Return True
            End Try
        End If
    End Function
    Public Shared Sub BringExcelWindowToFront(xlApp As Excel.Application)

        Dim caption As String = xlApp.Caption
        Dim handler As IntPtr = FindWindow(Nothing, caption)
        SetForegroundWindow(handler)
    End Sub

    Public Shared Function SaveWorkBook(xlBook As Excel.Workbook, initialFileName As String, initialPath As String) As Boolean

        Dim excelApp As Excel.Application = excelSheet.Application
        Dim excelWorkbook As Excel.Workbook = excelSheet.Application.ActiveWorkbook

#If DEBUG Then
        excelApp.Visible = True
#End If

        Try
            'Create the Excel Application object
            'Try
            'mooved to 
            'excelApp = New Excel.Application()
            'Create a new Excel Workbook
            'excelWorkbook = excelApp.Workbooks.Add(Type.Missing)
            'If excelWorkbook.Worksheets Is Nothing OrElse excelWorkbook.Worksheets.Count = 0 Then
            '    excelWorkbook.Sheets.Add(Count:=1, Type:=Excel.XlSheetType.xlWorksheet)
            'End If

            'If excelApp.Workbooks Is Nothing OrElse excelApp.Workbooks.Count = 0 Then
            '    excelWorkbook = excelApp.Workbooks.Add(Type.Missing)
            'End If
            'excelWorkbook = excelApp.Workbooks(1)
            'excelSheet = CType(excelWorkbook.Worksheets(1), Excel.Worksheet)

            'Catch ex As Exception
            '        excelApp = Nothing
            '        excelWorkbook = Nothing
            '        Throw New Exception("Can't initialize Excel application. Error: " & ex.Message)
            '    End Try

            excelApp.Visible = False
            excelApp.ScreenUpdating = False
            'Dim sheetIndex As Integer = 1
            Dim col, row As Integer

            If String.IsNullOrEmpty(worksheetName) = False Then
                Dim lenght As Integer
                If worksheetName.Length > 30 Then
                    lenght = 30
                Else
                    lenght = worksheetName.Length
                End If
                excelSheet.Name = worksheetName.Substring(0, lenght)
            End If

            ' Copy each DataTable as a new Sheet
            'For Each dt As System.Data.DataTable In dataSet.Tables

            'sheetIndex += 1

            ' Copy the DataTable to an object array
            'Dim rawData(dt.Rows.Count, dt.Columns.Count - 1) As Object

            '' Copy the column names to the first row of the object array
            'For col = 0 To dt.Columns.Count - 1
            '    rawData(0, col) = dt.Columns(col).ColumnName
            'Next

            Dim colCharset As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            Dim colCharsetLen As Integer = colCharset.Length


            ' Copy the values to the object array
            Dim result As Decimal
            For col = 0 To dt.Columns.Count - 1
                Dim rawData(dt.Rows.Count, 0) As Object
                rawData(0, 0) = dt.Columns(col).ColumnName
                For row = 0 To dt.Rows.Count - 1
                    '#If DEBUG Then
                    'If col = 8 Then
                    'Debug.Print(dt.Rows(row).ItemArray(col).ToString)
                    '    Debug.Print(dt.Rows(row).ItemArray(col).ToString.ToLower.Contains("=").ToString)
                    'End If
                    '#End If
                    result = 0
                    If convertNumberStoredAsTextToNumbers = True AndAlso
                        dt.Rows(row).ItemArray(col) IsNot Nothing AndAlso
                        IsDBNull(dt.Rows(row).ItemArray(col)) = False AndAlso
                        Decimal.TryParse(dt.Rows(row).ItemArray(col).ToString.Replace(".", Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator), result) = True Then
                        Try
                            rawData(row + 1, 0) = result
                            'rawData(row + 1, 0) = CType(dt.Rows(row).ItemArray(col).ToString.Replace(".", Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator), Decimal)
                        Catch ex1 As Exception
                            Debug.Print(ex1.Message)
                        End Try
                    Else
                        Try
                            rawData(row + 1, 0) = dt.Rows(row).ItemArray(col)
                        Catch ex1 As Exception
                            Debug.Print(ex1.Message)
                        End Try

                    End If
                Next
                Dim currentColLetter As String = String.Empty
                If col + 1 > colCharsetLen Then
                    currentColLetter = colCharset.Substring(
                 (col) \ colCharsetLen - 1, 1)
                End If

                If col = 0 Then
                    currentColLetter = "A"
                Else
                    currentColLetter += colCharset.Substring((col) Mod colCharsetLen, 1)
                End If
                Dim excelRange As String = String.Format(currentColLetter & "1:{0}{1}", currentColLetter, dt.Rows.Count + 1)
                excelSheet.Range(excelRange, Type.Missing).NumberFormat = "@"
                excelSheet.Range(excelRange, Type.Missing).Value = rawData
                rawData = Nothing
                excelRange = Nothing
            Next

            ' Calculate the final column letter
            'Dim finalColLetter As String = String.Empty
            'Dim colCharset As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            'Dim colCharsetLen As Integer = colCharset.Length

            'If dt.Columns.Count > colCharsetLen Then
            '    finalColLetter = colCharset.Substring(
            '     (dt.Columns.Count - 1) \ colCharsetLen - 1, 1)
            'End If

            'If dt.Columns.Count <= 1 Then
            '    finalColLetter = "A"
            'Else
            '    finalColLetter += colCharset.Substring(
            '  (dt.Columns.Count - 1) Mod colCharsetLen, 1)
            'End If


            '' Fast data export to Excel
            'Dim excelRange As String = String.Format("A1:{0}{1}", finalColLetter, dt.Rows.Count + 1)
            ''excelSheet.Application.ReferenceStyle = Excel.XlReferenceStyle.xlR1C1

            'Dim sw As New Stopwatch
            'sw.Start()
            'excelSheet.Range(excelRange, Type.Missing).NumberFormat = "@"
            'excelSheet.Range(excelRange, Type.Missing).Value2 = rawData
            ''excelSheet.Range("A1", Type.Missing).Resize(dt.Rows.Count + 1, dt.Columns.Count).Value2 = rawData
            'sw.Stop()
            'Console.WriteLine(sw.ElapsedTicks.ToString)
            'rawData = Nothing

            ' Mark the first row as BOLD
            CType(excelSheet.Rows(1, Type.Missing), Excel.Range).Font.Bold = True

            excelSheet = Nothing
            'Next

            If saveAsFileNameWithPath IsNot Nothing AndAlso String.IsNullOrEmpty(saveAsFileNameWithPath) = False Then
                Try
                    excelWorkbook.SaveAs(saveAsFileNameWithPath, Excel.XlFileFormat.xlExcel12, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Excel.XlSaveAsAccessMode.xlExclusive, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing)
                Catch ex As Exception
                    Trace.WriteLine("Can't save as " & saveAsFileNameWithPath, "DATA")
                End Try
            End If
            ' Save and Close the Workbook
            'excelWorkbook.SaveAs(outputPath, XlFileFormat.xlWorkbookNormal, Type.Missing, Type.Missing, Type.Missing, Type.Missing, XlSaveAsAccessMode.xlExclusive, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing)

            'excelWorkbook.Close(True, Type.Missing, Type.Missing)

            'excelWorkbook = Nothing

            ' Release the Application object
            'excelApp.Quit()
            excelApp.ScreenUpdating = True
            excelApp.Visible = excelIsVisible

            ' Collect the unreferenced objects
            GC.Collect()
            GC.WaitForPendingFinalizers()
            Return excelApp
        Catch ex As Exception
            If Not excelApp Is Nothing Then
                excelApp.Visible = True
            End If
            Throw ex
        Finally
            excelSheet = Nothing
            excelWorkbook = Nothing
            excelApp = Nothing
        End Try

        Return Nothing