@decodx
You don't have to report each and every post/thread of that user. If they all break the same rule, you can just report one, and in the feedback you write something like:
This user has created 16 low-quality threads within 2 hours. All of them are spam promoting his own website. Please check his post history and delete all threads created on (date and time the threads were created here).
From your report admins will be able to see that his only goal is to promote some website and delete all posts were rules were broken.
Thanks Pmalek, that's what I did.
I have opened this topic so that I can explain better and refer to it when I report to the moderator. I guess it helped because his posts were removed shortly thereafter.