spam being received with no referrer in the email log
One of our clients has received a huge amount of spam today, and on checking the email log the majority of them don't include a referring page. The majority is coming from one IP range so I've banned that range in the htaccess file, but I'm wondering how they're managing to send spam without visiting a page with a contact form on it? Are they triggering the PHP script directly? I've attached a screengrab which shows some sample entries in the email log.
*Update* - just remembered that the mail script is using smtp to send via the client's own domain which we don't host. Does this therefore mean I'm wasting my time trying to ban IPs via the htaccess file or on our server and that the issue needs to be dealt with at the client's end? Even after adding the IP ranges to the htaccess files, the emails are still coming in.