I noticed that none of the dunning letters I receive ever have a dated post mark. And usually the letter is dated a week or more before I actually receive it so it looks like they are sending it out earlier than they actually do.
Anyway, that got me thinking. Since we have 30 days from the DAY OF RECEIPT of a dunning letter to send our DV, what happens if you claim you never received a dunning letter but the CA says they sent one out? They don't send anything certified mail w/ return receipt! Or even anything with any tracking number/delivery confirmation available.