hide user info?

Hi,

I am almost ready to launch a blog. I need to make absolutely sure that people who post comments can remain anonymous. The way the blog is set up, in a comment all you see is

————–
username
dd/mm/yyyy

Comment text.
————–

I see no obvious way to find the user’s email. Is this mainly a function of what the templates display? Could someone who knows WordPress add something to the URL and find out a poster’s email?

Thanks,

Ben