Info about Private Messaging and a mystery solved for me that other's may have been wondering about:

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Quote:

4.3.3: The Outbox When you send a PM, the message goes to your Outbox. It remains in the Outbox until the recipient visits his/her Inbox, at which point it is moved from your Outbox to their Inbox. While the message remains in your Outbox you may edit or delete your post if you like. The message remains in your control until it is received.

(bolding mine)

I had sent a PM to someone and it didn't go into my sent box, was there a few days later still. I thought something was wrong, expecting it to act like my computer's email program, where as soon as you hit "send", the message gets but in your "sent" folder. But the PM system doesn't work that way. So don't delete messages in your Outbox, thinking they already made it to someone's Inbox.

That is one way you will know if someone did not read your PM, by if it is still hanging out in your Outbox. If after a few days your PM to someone is still waiting in your Outbox, best to email the person with regular email, as maybe the person did not come to the forum to note any new private messages.