I'm pretty sure they don't test them. I got a good one the other day from a well known institution. It was a bill and the html part said I owed N amount but the

I'm pretty sure they don't test them. I got a good one the other day from a well known institution. It was a bill and the html part said I owed N amount but the plain text said 0.00. By default I read the plain text part but when I saw it says 0.00 I thought it was odd so checked the html and there it was the correct amount!