Bumping Posts
You are allowed to bump old threads only providing it is with a post that contributes to that thread's original topic rather than that thread's current topic of conversation (i.e. replying to someone from 2 years back is not cool). In fact it is generally preferred over making a new thread. However, any bumping of threads that do not meet these conditions are frowned upon, and will probably result in post deletion. Likewise, do not respond to dead threads when they are bumped to tell the person in question not to necrobump, since such posts are considered to be spam.