Private Messages

I don’t use PM’s much but I am confused over the difference between outbox and sent box.
For example, today I sent a PM and pressed the ‘submit’ button.
The PM went into my outbox but has still not appeared in my sent box.
So has it been sent? or do I need to do something else to actually send it.
Why is there an outbox and a sent box – all other forums I use have only an in box and an out box.
Answer #1
It will appear once the user to whom you send a PM has opened your PM, until then it is on outbox.
While it is in outbox you can edit it, delete it.
EDIT:
Other forum (medianxl) – also have outbox and sentbox.
Answer #2
When you send A PM it will will stay in the Outbox until it’s been read..
Once it been read it will go to your sent box..Sent box stores all the PMs you ever sent until you delete them..
Answer #3
O.K. thanks for that, I understand now.