When a user (i.e. a user in the newly registered group) creates a post that needs approval, he/she will see the information that his post is awaiting approval after clicking on submit. Unfortunately, most users just click on "Return to the forum last visited" without even reading the note. After that, the user won't be able to see the topic or post he/she has submitted and therefore a lot of users create the topic or post again.
My proposal is to show the users the topics they have created in the viewforum page and the posts in the viewtopic page even though they are still not approved.