There is no email authentication yet for every ads posted. This is because users are required to register in order to post and so it would might seem a redundancy.
I am thinking that you may have a different classifieds setup which requires ad authentication and so in the mean time please post a request on this feature at the ideas exchange page http://ideas.appthemes.com/classipress/?orderby=votes.
Please help our moderating team work more efficiently by not sending us support questions via PM. You can read more about how AppThemes support works here. However, you can send a PM to follow up and remind me if I missed your support request/thread.