It is not exactly clear what you are trying to achieve, but the basic code to replace text in a message body is
Sub ReplaceText()
Dim olItem As Outlook.MailItem
Dim olEmail As Outlook.MailItem
Dim olInsp As Outlook.Inspector
Dim wdDoc As Object
Dim oRng As Object
Const sFindText As String = "%Company%"
Const sReplaceText As String = "The Widget Company"
Set olEmail = ActiveExplorer.Selection.Item(1)
Set olItem = CreateItemFromTemplate("C:\Users\test.oft")
With olItem
.subject = olEmail.subject
Set olInsp = .GetInspector
Set wdDoc = olInsp.WordEditor
.Display
With oRng.Find
Do While .Execute(findText:=sFindText)
oRng.Text = sReplaceText
oRng.collapse 0
Loop
End With
End With
lbl_Exit:
Exit Sub
End Sub