I am aware that the issue of spam bots in chat, within the trade hubs is already on the scope for CCP. But I am curious as a short term and immediate fix, why you haven’t enabled/added a "right click on the player, ‘ignore channel posts from…’ " Option.
No matter if those people are bots or actual New Eden Members… a simple option to add too / remove from “ignore list” would be perfect… all chat channel messages and private msg request would be ignored, only EVE Mail would still be available, since that kind of communication leaves an easier/better tracking mechanism and is hard to spam in bulk.