Yes well this is a unfortunate side effect. We have to do all that we can to protect our members but at the same time we have to allow the most freedom possible. So in the end there is always a trade off.
We allow our users not to be spammed but now users with less than 40 posts can not PM.
All we can say is contact them VIA Email or IM. Right click on the user name and when the profile page comes up you will see if they have EMail support or not. If so send them a PM via that. It will go thru the forums to them.
If there was another way to stop the spam we would. But this is something that we feel we have to put in place. We have tried everything up to this point to stop it. But when Pr0n PM's are being sent. We have to take action and sometimes that action is not always fair to new users. For that we are sorry. If we could come up with a better solution we would.
We are open to suggestions. We have a forum just for that just a few down from here.