When you type them and hit send, they are placed in your outbox.
When the sent to reader opens the PM, it is automatically moved from the Outbox to the Sent Folder. This lets you know that the reader opened the message.
If the reader doesn't open the message after a couple of months, you might check the last time that they posted. They may well not be active any more, or may have had their accounts locks for spamming the board with stupid one liners.
SOME PEOPLE TRY TO TURN BACK THEIR ODOMETERS. NOT ME. I WANT PEOPLE TO KNOW WHY I LOOK THIS WAY. I'VE TRAVELED A LONG WAY, AND SOME OF THE ROADS WEREN'T PAVED. ~ Will Rogers