Based on your code, you would need something like the following - see the note at the top of the macro

Option Explicit

Sub SendWorkBook()
'Graham Mayor - https://www.gmayor.com - Last updated - 04 Jun 2019
'This macro requires the code from
'http://www.rondebruin.nl/win/s1/outlook/openclose.htm
'to open Outlook

Dim oOutlookApp As Object
Dim oItem As Object
Dim olInsp As Object
Dim wdDoc As Object
Dim oRng As Object
Dim i As Integer

Set oOutlookApp = OutlookApp()    'Use the function from http://www.rondebruin.nl/win/s1/outlook/openclose.htm
    'to open Outlook, or it will not work correctly
    For i = 2 To Range("a100").End(xlUp).Row
        'Create a new mailitem
        Set oItem = oOutlookApp.CreateItem(0)
        With oItem
            .Subject = Cells(i, 4).value
            .Attachments.Add Cells(i, 5).value
            .To = Cells(i, 2).value
            .CC = Cells(i, 3).value
            .BodyFormat = 2    'html
            Set olInsp = .GetInspector
            Set wdDoc = olInsp.WordEditor    'access the message body for editing
            Set oRng = wdDoc.Range
            oRng.Collapse 1    'set a range to the start of the message
            'enter the range text
            oRng.Text = "Dear " & Cells(i, 1).value & vbCr & vbCr _
                        & "Please update your file." & vbCr & vbCr _
                        & "Please feel free to contact me if you need any clarification."
            'display the message - this line is required even if you then add the command to send the message
            .Display
        End With
        DoEvents
    Next i
    'Clean up
    Set oItem = Nothing
    Set oOutlookApp = Nothing
    Set olInsp = Nothing
    Set wdDoc = Nothing
lbl_Exit:
    Exit Sub
End Sub