Actually that's not a great idea. A notice that the recipient is
expected to handle information with unusual attention to
confidentiality is required by law to stand out so that there isn't
any ambiguity about the duties demanded of the recipient. Trade secret
cases have been lost because a sender relied on the email boilerplate,
the recipient produced intentionally public emails with the same
boilerplate, and the recipient asserted that he had no reason to
believe the particular message was any more sensitive than the
sender's routine public messages.
The use of the words "intended recipient" are also extremely problematic;
by definition, if it is addressed to me, I can be construed as being the
"intended recipient." If I then turn around and forward it to you, you
are now also an "intended recipient." Nice, eh.