Private site invisible to search engines?

Goal: a web site that is relatively private. Viewers will find the
pages through links in e-mails. We will make no effort to have the
pages appear in any search engine; if it is possible to disable
listing at search engines (should they be found) we'd like to do that.

Obviously, once the e-mail is sent out, someone could put a link
somewhere public, and Google could find it. But if nobody posts a
link, how would any search engine find it?

Where can I learn more about this- whether it is possible, and how to
disable listing by search engines? Thanks

keyword: 72611547