Many sign up forms will ask you for an email address so that they can contact you.
Even the most minimal sign-up (other than no sign up) will need an email address to send you a validation email.
Frequently we see copy that says
we will never send you spam
(well that depends on what you consider spam... unsolicited emails about discouts)
we will never sell or rent your email address
(incomplete, eg doesn't preclude actually giving it away)
we will only ever use your email address to communicate with you about your orders
(really - that's a bit restrictive actually)
Occasionally we get a light hearted or casual message like this one from Wufoo, which seems like a good option, but is casual really the best approach?
Sometimes we see links to Privacy policies or terms and conditions, that few people actually read.
Or maybe the matter should not even be raised in the user's mind?
What's the best way during a sign-up process, to instill confidence in a user that their valuable email address is safe?