Frankly I don't see why you need to create a new message. Why not simply edit the message you have, given that it is system generated? Something like the following should work - note the comments in the code - especially the first one as you'll need to download some code.
Option Explicit
Public Sub sofWorkWithOutlook()
Dim olApp As Object
Dim olNs As Object
Dim olFldr As Object
Dim olMail As Object
Dim olInsp As Object
Dim wdDoc As Object
Dim oRng As Object
Dim strNum As String
Dim xlSheet As Worksheet
Dim LastRow As Long, lngRow As Long
'Use the code from the link below to start Outlook properly from Excel
'http://www.rondebruin.nl/win/s1/outlook/openclose.htm
Set olApp = outlookApp()
Set olNs = olApp.GetNamespace("MAPI")
Set olFldr = olNs.GetDefaultFolder(6)
Set xlSheet = ActiveSheet
With xlSheet
LastRow = .Cells(.Rows.Count, "A").End(xlUp).Row
For lngRow = 2 To LastRow
strNum = .Cells(LastRow, 1)
For Each olMail In olFldr.Items
If TypeName(olMail) = "MailItem" Then
If (InStr(1, olMail.Subject, strNum, vbTextCompare) > 0) Then
With olMail
Set olInsp = .GetInspector
Set wdDoc = olInsp.WordEditor 'access the message body for editing
Set oRng = wdDoc.Range 'orng is the message body
'.subject 'is the message subject. Edit it as required
.display
'edit oRng as required
.Save
.PrintOut
Exit For
End With
End If
End If
DoEvents
Next olMail
DoEvents
Next lngRow
End With
Set olMail = Nothing
Set olFldr = Nothing
Set olNs = Nothing
Set olApp = Nothing
End Sub