Suggestion regarding spam

Seems that TN Forum has had lately more spamming than before. This time I don't mean the erection threads and other repeated nuisance but pure, commercial, non-nudist spam. Would it be possible to introduce measures against it, like for instance 5 or 7 days quarantine period after registration before any postings to Forum allowed? Such simple measure might work well as most spammers have a short fuse and keeping some login data for more than few minutes might be too much for them.