from my own experience:
Mr Magic wrote:any new poster must lodge a valid email address or he/she/it doesn't get access to post?
very easy, it's a basic forum system setting
Mr Magic wrote:
(They should also need to provide their real named/address details to the mods, so that they can't just make up a nondsescript email address for the purposes of circumventing this rule.)
impossible to verify, so pretty pointless
----------- the next bit is a wall of text of why it's kind of pointless for either option as well as other pointless options -----
unfortunately providing a valid email address isn't much of a deterrent as it's pretty easy to get a free email address to use for forum signups. In fact most data security people tell you to use a fake/alternate email address for every different thing you sign up to on the internet as a basic form of security.
What some modern forums allow is the ability to not only ban usernames, but also the IP address that they were logged in from - the only issue with this is that unless you have a fixed IP address (which most people don't have unless they are logging in from some workplaces), chances are someone who has never done anything wrong may end up getting blocked from the site due to the random IP they get assigned every time they turn their router/modem/computer on is one that has previously been banned.
It's pretty rare, but since most people posting here (including the trolls) are based in Melbourne and the likelihood is they are using one of the big 3 providers (telstra/optus/iinet), it actually makes the chance of getting assigned one of those random IP's more likely as each provider only has access to a limited pool of addresses to assign from.
---TL;DR (too long, didn't read)
mods/admins could do this, but it's essentially a waste of time as anyone who wants to troll the forum will do it easily enough
edit one other option that may be useful is that you can set new signups to not be able to post until their first post is verified by an admin/mod - that should the stop the idiots