As @eleman suggested: Outlook.com
Otherwise, if you just want to be anonymous when signing up to a website that insists on your giving an email address, you could use MaskMe.com (FREE Firefox add-on) for email. I use it all the time. It's very handy and preserves your anonymity and enables you to avoid spammers/hackers getting your real email address. It generates a random and unique proxy email address for you for each instance you use it (e.g., similar to email@example.com), and all email addressed to that address goes to the real email account you have designated, where it appears showing you what the proxy address was. So you can always tell which person/organisation sent you that email or passed it on to another sender.