A quick and more secure way to do this would be to use
if ($address($nick,2) = ADDRESS OF JohnDoe) { ... }
Actually, if you're going to do that, you'd want to use:
if ($wildsite == *!*@address.of.johndoe.com) { ... }
or
if ($site == address.of.johndoe.com) { ... }
If the person has a static IP/Host, using a static match is fine. If the persons address changes often (such as the person being on 56k), you would want to use my suggestion in my first post.
$fulladdress returns nick!ident@hostmask.com
$wildsite returns *!*@hostmask.com
$site returns hostmask.com