I'm going to voice a "NO, NO, NO!!!!" on the certified mail route. Nuh uh. You don't want to do that. What purpose would it serve? Showing that they GOT the letter? It might make them think you have some ulterior motive for the need of a receipt.

A better suggestion, might I say, is using a certificate of mailing.

http://www.usps.com/send/waystosendm...ingservice.htm

First of all, when you use THAT only YOU have evidence that you mailed it--the doctor doesn't.

Second of all, you can staple the certificate to a copy you keep for yourself (your letter) and then if they say that they never got it, you pull out the certificate and the letter you sent.

Using a certificate of mailing raises a presumption under the law that the item was mailed. Basically the presumption is that once you've put the item in the mail, the one receiving it has received it already. That's a fiction, of course, but it means that we trust the USPS to get the item to another person without fail.

And try proving that you didn't get something in the mail. Dare ya to show you didn't get a piece of mail. I'd rather prove that I mailed something.