I just think that if someone got muted system messages should be blocked as well. While impractical, using tiny tips or the name changing it's still possible to spam the chat.
Limiting the chat to players who used the site already defeats the purpose of the chat, as people quite often ask questions before getting started.
this could be a good idea, OP should make a requirement to chat like you must wager at least 0.01 btc before you can chat, this will decrease the spam
This is good and practical idea there must be some wager requirement just like some other sites before qualify for chatting this will really help to minimize the spam problem.