I'm using this at the moment, and it works but it also strips all in-line images from the body which is not ok.
Is there a way to remove only this text at the top of the email but not break the formatting or contents of the rest of the email?

Sub ShrinkAlert(MyMail As MailItem)
    Dim body As String, re As Object, match As Variant


    body = MyMail.body
        body = Replace(body, "CAUTION! This is an EXTERNAL email originated from outside the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. ", "EXTERNAL:", 1, -1, vbTextCompare)


    MyMail.body = body
    MyMail.Save
End Sub
My source info:
Replace Text: https://superuser.com/questions/4640...rlink-in-outlo
Enable Run Script rule: https://www.slipstick.com/outlook/ru...-script-rules/
Allow Macros: https://www.techrepublic.com/article...0(Figure%20A).