First add a chat limit of like 2 or 3 per minute so the sellers cant spam nonstop.
Second add a level 25 minimum requirement to chat in normal.
Third add a button called Block/Report Spammer which will automatically report every gold seller message and block them at the same time which is very useful since i just block them not report normally cause they spam when im doing something and i rather not see the message then try and find the report button.
Of course this only covers it up a bit and you still need to get rid of the sellers and bots.
I recommend a simple captcha every hour that pops up at a random time during each hour. It would need to be hosted server side instead of client side to make sure they couldn’t bypass it besides doing the captcha.
Not the old style of the new kind where bots cant analyze or guess what letters or numbers are in it even if they look at a clear crisp image of it. In fact there are captchas so good that it literally makes it impossible for anyone but a human to ever put the right code in because with the new age captchas they make things so random and with so much stuff that only a human eye can tell what the code is.
Cant remember the name of it but you could always make your own.
Add like a 3 strike your out system for normal people not to get screwed by it. I think its fairly simple although i can see that as an annoying mini process that would take people out of being immersed by the game.
In game gms would also easily ban all spammers but for some reason no mmos ever want to even consider having at least 1 person go around banning all the spammers and bots and the ones that do do it have much better games for it.
Well anyway that’s my two cents and im sure there are flaws but its a simple, easy and real solution to get them out of the game and put all the anti bot stuff that makes the game more annoying to play like the market stuff and dungeon limits etc away in exchange for a single minor annoyance.
You also need to remember when the game goes f2p there will be tens of thousands of bots and they can make a new bot account every single second literally. You guys are going to need some serious effort if you dont want the game to die off with so many spammers that you cant even read the chat cause it will be scrolling that fast.
As it is will all popular f2p mmos
Hope that helps.