A few months ago, I had an experience that made me re-think internet safety. I'm a trustworthy person, therefore, I trust. But I now think before I send emails.
What I've learned is never to send an email and include other people's email addresses. It's like giving away someone's phone number. Or their home address. Email is the way we run our world and by giving away someone's email address, you are compromising their privacy.
And although you may think it's ok to do it, because you know everyone on that cc, be aware because what you know of someone, might not be all that you need to know.