I think what the GP is implying is that even a 95%-accurate email address validator would suffice, because any email address you care about is going to get furt

I think what the GP is implying is that even a 95%-accurate email address validator would suffice, because any email address you care about is going to get further validation when you validate the address as functional. So it's wasted effort, and suggests poor business sense and a need for close supervision.