Anonymous posting

[account_inactive]

One idea would be to require a login but have a sub-forum for anonymous posts.  That way the admins & mods would know who posted what but no one else would.

Of course, if someone wants to post anonymously, there are forums out there that allow that, in fact, "Onion" forums with hidden addresses, but I would avoid those, as there is quite of bit of evil things in the Deep Web (drugs, illicit porn, terrorism, etc.)

Actually, most of the "Onion" forums require you to register an account. You've just got the layer of anonymity through Tor but people can still connect your posts to you.

By anonymity in this context, EP and others mean what you said in your first sentence. It would just come up "Anonymous" but moderators would still be able to see the account name or the IP.