The way I see it, is everyone is unblocked. He opend a chat with "blah@hotmail.com" and it blocks everyone else. Then closing that chat unblocks everyone.
Opening another chat does the same thing.
That way he only talks to one person at a time.
Personally, I think a /blockall command, an /unblockall, and a /block <email> command would be good. Applying to everyone except the current chat window >_>. Or /blockclosed (for no current chat) and /blockopen (for all open chats).
Yep

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