I know that you can block someones email address through webmin. What happens to the emails when the email address is blocked?
Does it go into cyberspace or is it stored on the webserver?

Tnx.

I know that you can block someones email address through webmin.
Webmin is a GUI for administering various mail servers. Without specific details about the mail server you're configuring via webmin, and details of its webmin module, it's hard to answer this question.

What happens to the emails when the email address is blocked?
Does it go into cyberspace or is it stored on the webserver?
Under sendmail, there are the options DISCARD and REJECT for use in the access.db file, which will either bounce the mail, or silently discard it. See http://www.faqs.org/docs/securing/chap22sec178.html for further information.