The issue here was not primarily about deception. It seems mainly to be that (a) at least one recipient interpreted their mail as a legal threat, and (b) it was a mass-mailing. Spend a minute thinking through the implications if that were true, and you get a firestorm.
I suspect visibility plays a role in the comparison you're making; out of sight, out of mind and all that. But much more importantly, someone sending you what you think is a legal threat is a lot more salient.
I suspect visibility plays a role in the comparison you're making; out of sight, out of mind and all that. But much more importantly, someone sending you what you think is a legal threat is a lot more salient.