when i was playing DAoC, we had quite a lot of spammers, so i put this suggestion to the devs:
"if a message contains [blocked word] then auto-ban the player"
it took them a couple weeks to code it, but when they did, the spam stopped immediately.
for example, we had a guy last night promoting what .. "viod.ch" or something like that; for ease of this discussion, let's say games.com
when anyone writes the string games.com, then suspend the account.
they are all weird foreign websites and i bet no legit AT user has ever typed that; and even if they do, when an admin comes around they can unban them. at worst, a brief nuisance.
this has the advantage that you only need to block spam FOR one source, not FROM one source, just once.
so if for example, chinaproduct.com asks their employees to spam AT, you don't need to manually ban every account, just ban that phrase once.
or just prevent the forum from creating the thread if there is the "forbidden phrase" in the post.
or even better (inspired by Titanfall), make the thread invisible to anyone except the spammer.