You can tell if you post links and comments that never get voted on or replied to (I presume, unless hellbanning reports false votes). If you have showdead ena

You can tell if you post links and comments that never get voted on or replied to (I presume, unless hellbanning reports false votes). If you have showdead enabled, which is an option after you pass a certain karma threshold, you'll see posts and comments from hellbanned users. Most of the posts are simply spam, which is fine. Many of the hellbanned users, however, don't appear to have done anything wrong. You can pinpoint when they were hellbanned by checking their comments until you find one that isn't dead. Either that or one of the comments immediately preceeding it, or a post that tripped the spam detector, is usually responsible. Hellbanning is done both by the spam detector as well as by mods. Unfortunately, there really isn't any transparency in the process, nor is there much anyone can do to reverse it. You can send an email to info@ycombinator.com, but I don't know of anyone successfully being unbanned by doing so.