@Compuware you can block the content from being sent.
Our current setup: we have a competitor field at the company level, which copies to the contact competitor field via a workflow. This way if a contact that is a competitor is deleted any new contacts from that orginization will be marked competitors.
Additonally we have a dymanic list of all contacts with the competitor field set to yes. Then on a given workflow that sends content we use the “competitor” list as the workflow suppression list.
So if you are a competing company and submit a form, the newly created contact is marked as competitor, added to the list and suppressed from completing the workflow that emails the content.
Let me know if you have any questions.