I make and sell soap. The soap contains an ingredient that anyone can use to make bombs. Some people buy my soap only for that purpose. I know because they literally tell me how they use my soap. I can remove that ingredient but I would loose a lot of sales.
The police finds my soap in the lab of someone who blew up a building. Some people died. Was it my fault, knowing how it was being used? Did I do anything illegal? Unethical? Immoral?
Interesting thought experiment, but no, I don't think it's llegal/unethical/immoral to sell that soap. But in practice this sort of business will change their formula to avoid bad press and regulation.
Having done some internet things (email stuff) that have been abused by others I always felt obligated to make the abuse as hard as possible once I found out about it.
I am not sure about the legal standpoint, but from a moral one I would have felt bad running the business knowing it's regularly abused to harm others and I am not doing anything against it.
The police finds my soap in the lab of someone who blew up a building. Some people died. Was it my fault, knowing how it was being used? Did I do anything illegal? Unethical? Immoral?