Spam

The following .htaccess code will block spambots from accessing wp-comments-post.php directly:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_METHOD} POST
RewriteCond %{REQUEST_URI} .wp-comments-post\.php*
RewriteCond %{HTTP_REFERER} !.*yourdomainname.* [OR]
RewriteCond %{HTTP_USER_AGENT} ^$
RewriteRule (.*) ^http://%{REMOTE_ADDR}/$ [R=301,L]
</IfModule>

Source: http://www.wprecipes.com/reduce-spam-on-your-wordpress-blog-by-using-htaccess

I would like to use this on a multi-site setup, however, the domain name (yourdomainname.com) is hard-coded. Is removing the domain name a safe solution?