<p>So you are spamming anyone who joins the chatroom.</p>

<p>I'm puzzled how you could even think that assaulting anyone who joins the chatroom could be appropriate. It's bad enough when people do that manually, but automatically‽</p>

<p>Any auto-greet message is spam and that makes the auto-greeting bot a spammer. Banning that bot was appropriate. Letting the bot run was not appropriate.</p>

<p>A bot should never ping a user who didn't opt in.</p>

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<p>I've <a href="http://meta.stackexchange.com/questions/207158/require-two-clicks-to-join-a-chatroom">proposed a change to the chat interface</a> that would make this issue moot. If joining a chat room was an affirmative step, rather than the automatic and potentially accidental thing that it is now, I would have no objection to users joining a chat room being greeted. (Not that it would necessarily be a good idea, but it wouldn't be spamming undemanding users.)</p>