Yep ( http://federalevidence.com/node/784 ) ; mail properly addressed is assumed to be delivered. For related reasons, any mail sent to a business is assumed to have been read. This is a rebuttable presumption.
Even knowing this, many lawyers (and other savvy people) send certified mail with a return receipt. It strengthens your case in the event that the other party tries to disavow receipt of the mail, and it says (rather loudly) that there is a folder on your desk labeled Evidence and that every additional action the other party takes will join that folder.
Even knowing this, many lawyers (and other savvy people) send certified mail with a return receipt. It strengthens your case in the event that the other party tries to disavow receipt of the mail, and it says (rather loudly) that there is a folder on your desk labeled Evidence and that every additional action the other party takes will join that folder.