I am wondering if it would be legal for party A to invoice a company which posts spam advertisements on a website owned by party A which has a terms of service prohibiting such unsolicited and unauthorized posting.
Put another way, could party A consider the spam posting (which would have links back to a service or product of the spammer) to be advertising, and then bill the spamming company in the amount of the standard advertising fee and any labor associated with the spam?
I am thinking of it like this: If party A owned a roadside billboard, on which it sold advertising space, and someone without authorization posted their own ads on that billboard, perhaps the billboard owner is entitled to seek remedies for that?
If so, what would the website's terms of service need to include for that to be able to be enforced?