We look after a low volume website which has a contact us form which looks like this:
<form method="post" action="http://www.*****.com/cgi-bin/contact.cgi">
Starting a few weeks ago, every few days we receive an empty form submission. No subject, no nothing. They must be bypassing the submit button and hitting the server directly because if I submit even an entirely a empty form (validly, via the browser) I get subject line. Additionally, the form is working because valid forms with genuine customer enquiries are coming through too, one every few days.
The IP address is always the same. Checking the IP address all I can see is it's a webhosting outfit in Germany.
I don't think it's causing us a problem. But the customer wants to know why it happens.
What are the range of possible explanations to tell him?