Why “Content-Length: 0” in POST requests?

Question

A customer sometimes sends POST requests with Content-Length: 0 when submitting a form (10 to over 40 fields).

We tested it with different browsers and

Answer 1

Are you sure these requests are coming from a "customer"?

I've had this issue with bots before; they sometimes probe sites for "contact us" forms by sending blank POST requests based on the action URI in FORM tags they discover during crawling.