What the heck is hobby.2ndquadrant.com?

There are a few threads floating around currently in which some of
the cc'd addresses are various-people at hobby.2ndquadrant.com.
Addresses like that seem not to work, or at least not work reliably.
I believe the official addresses are just soandso at 2ndquadrant.com.

If you're replying to any such threads, you might want to clean
up the addresses so you don't get a bunch of bounce messages.

In any case, I thought the 2ndquadrant people would want to know that
there's something broken in their mail system.  I'm not sure how these
addresses got injected into our threads in the first place, but I bet
it wasn't done by anybody outside 2ndquadrant.  Perhaps an internal
mail server name was unintentionally exposed?
        regards, tom lane