http://www.perlmonks.org?node_id=206636


in reply to Re: Detecting an email address
in thread Detecting an email address

Of course, webbugs are easy to defeat if you've disabled all scripting in your email client (or it doesn't support HTML) and you've set your firewall to only allow it to connect to set mail servers on set ports (ie Outlook can only connect to ports 25 and 110 - all other access is blocked by my firewall: therefore webbugs on port 80 will fail).