I don't know how things are handled here, but I've been a moderator on another non-diving related message board for a while now.....
Welcome, warren_l! Greetings to our newest member, alluma1!
Current Members: 71,067, Threads: 32,660, Posts: 189,227, Online since 22-02-2003
And we see some pretty substantial post volumes, which inevitably results in some inappropriate posting. The mods do not generally delete posts or threads, but instead move the thread to a temporary location where we can trash or re-instate it if it is appropriate. There is always an explanation given to the offending member as to why an action was taken, and usually with the consensus of the moderating team. But we try to avoid deleting threads/posts altogether and especially without explanation to the membership at large. The same concept also applies to banning.
We've also introduced the concept of a "stealth ban" where the user is banned, and any further posting by the user is not seen by anyone else on the board except for the moderators and the user. The banned member does not realize that he is banned but just ends up responding and posting and seemingly everyone is ignoring him. Really quite entertaining, actually.