I don't think it needs to be more effective than legit spam. Send regular spam but have the links take them to an anti-spam education page, something short that

I don't think it needs to be more effective than legit spam. Send regular spam but have the links take them to an anti-spam education page, something short that they would remember. Like, "If this were a real spam you would now be prompted to buy X so that we can steal your identity and sell you fake products that could kill you. Good thing it isn't!"