You're making no sense whatsoever. You also didn't specify who you received this email from...I'm assuming Facebook. And I'm assuming you don't have a Facebook account yourself. If I'm understanding what you're TRYING to say, what is probably happening is that Facebook is accessing you through the email contact lists of your friends who DO have Facebook accounts. When you start an account with Facebook, they try to "import" contacts and help you find friends who are also on Facebook. They do this by accessing your contacts from the email account you used when setting up the Facebook account. So, basically, its not Yahoo doing this and nobody is accessing YOUR email contacts. Facebook is just finding you by digging through your friends' email accounts, including their sent and received mail most likely. I'm pretty sure your account is safe. Hope that helps.
In response, I really wasn't trying to be insulting. I tried to help you. Yes, Yahoo gives Facebook this info IF YOU HAVE A FACEBOOK ACCOUNT. Which is why Facebook has been given your email information by accessing your FRIENDS' email accounts. Because you are one of their contacts. The setting to uncheck to prevent this would be in your account settings ON FACEBOOK. Since you have no Facebook account there is nothing to uncheck. They are not accessing your email. They are accessing you through your friends' email accounts because your friends have Facebook. You received the email about your friends having Facebook accounts because Facebook thinks if they tell you all your friends are on there then you will want to join too.