Not sure. I know it doesn't let me respond to mail threads with people who've blacklisted me, so you might have to blacklist all 27 people (temporarily?).

It does if it's a group one*. DanWL knows this specially well :P

*Assuming you blacklisted only AFTER the thread was made. If done before, you can't be mailed.

After blacklisting people, whenever they post, your mail doesn't flash and you don't get an email notifying you that they posted. :)