[minalecs]

I'm not an expert but I don't think 4chan stores anything.. why do you need to ?

[radq]

I don't think this is true. This was is Christopher Poole's testimony:

  Q. Now, you said that 4chan does not keep the
  contents of these posts. Does 4chan maintain business
  records of web logs, also audit logs and sometimes banned
  entries as well, if a particular user has been banned?
  A. Yes.

http://www.scribd.com/doc/41691202/35688046-Christopher-Moot...

[relisys]

We do this for the safety and security of the site.We can't just allow any sicko to start posting inappropriate pictures on our site.

This is our way of keeping track and providing a safe and pleasant environment for everyone.

Thanks for asking.