Is there a way to Blacklist clients?

Is there a way to Blacklist clients?

Is there a way to add clients (accounts) on a blacklist, for example if they fail to pay?

I was thinking perhaps creating a 'Blacklist' button that could be ticked, and once selected prevents a Deal from being made for that particular account. Is there a workflow that could help me achieve this?

What would also be helpful is a way to identify at the lead stage that they are attempting to add a blacklisted client. An email notification would be helpful.

Thanks,

Miri