
These are thorny, fact-specific questions -- whether you are bound by terms of use that you have actually seen and choose to ignore. Since most web sites come with terms of use, it's no surprise to you that they're there and a reasonable person might be expected to check on them.
All of that having been said, the information is "out there" and it is difficult to imagine what the damages, if any, would be that the owner of the web site might sustain if you were to send a single email to these folks.
You should consult your own attorney for advice regarding this matter.
Other Answers
Using factual information like email addresses is not copyright infringement, as facts cannot be protected, However, if you use the email addresses in violation of the Terms of Use of the website, you may have breached your agreement with that website. You have to check all of the terms of the website to see how they enforce their Terms of Use.