After numerous spam to an email address I never send email from, so can only have been harvested or "guessed", I thought I'd try and get back at the spammers.
Here's the email I've just sent to the spam addresses and the company's domain contacts.
Tomorrow, it will be sent by registered post to confirm they've received it.
If there is no response after this, we'll be going to court.
Let's see how this pans out.