Basically, unless you already have an existing written NDA you’re likely not bound. Your company may have an NDA between yourself and a vendor, carrier or otherwise. If you’re not sure, ask.
Disclaimers are invalid on their face because they're an attempt
to unilaterally enforce contractual terms without a meeting of the
minds -- something required for a valid contract. They're "adhesions",
i.e., they're provisions so one-sided that it's immediately obvious
that they've been dictated by one side and not agreed to by both
as the result of some kind of bargaining or negotiation.
The two best references I'm aware of in this regard are:
"We can't help it--this really makes us nuts. When will these
people learn? You transmitted your crappy mind-numbing message
to us, in plain text, over the public internet. It's ours (and
whoever is sniffing our mail) to do with as we please and you
can't have it back, so piss off. We won't delete it, we will
publish it, we will forward it, and there is nothing you can do
about it. Go ahead, take us to court, but try to find a shred
of legal precedent first, ok?"
"First, such boilerplate contains useless adhesions, meaning
the explicit and implied threats they make are particularly
annoying. If you send something via email, the recipients (are
you sure you aren't sending to a mailing list?) and anyone else
who sees your clear text postcard in transit can undetectably and
with full deniability do whatever they want with the information
written on it in plain view. Even casual users of email know
email is not a secure communications medium. Thus the threats in
typical bogus legalistic boilerplate are naught but an attempt
at highly improper intimidation. Demands made in this manner
will be regarded as evidence of a hostile attitude on your
part by a significant portion of recipients. The threats will
negatively affect how your recipients perceive the other ideas
in your message."