Premium members only can do PMs (private messages). These run like threads but are in your PM area and each thread can only be read by the people invited to the thread by they person who starts the thread. Once a thread has started, no one new can be added.

Every few months we delete all private messages more than a year old (the system lets us do this automatically - we do not see the messages). But you can tidy up your PMs yourself and I just figured out an easy way today.

Go into your Private Messaging. Go to PAGE TWO of your messages. At the bottom of the page click SELECT ALL and then click the DELETE button. This selects all message on that page, and deletes them. Then the page refreshes showing all messages that used to be on PAGE THREE but are now on PAGE TWO!! Repeat until you have got rid of your old messages.

HOW DELETING PM THREADS WORKS
If you start the PM and delete it, it is deleted for everyone on the recipient list.

If you did not start the PM and delete it, it is only deleted in your list. People can continue posting in the PM, but you will never see it. You are marked as LEFT. See screen snap below.