The mxxxx email address is mine, the email@example.com was the spammer.
The reason why I thought this looked pretty dodgey and not just your usual harvest was because I had only just set up the discussion list, and only sent an email to 2 other of my own addresses, to test it and work out some settings and bugs before telling anyone about it, and I had it set on private.
I’ve never posted to any other list with this spork address and I only saw it for the first time while trying to get things sorted on the discussion list configuration.
So it does seem to be a very weird thing that it got grabbed like that, and readily admit I have little idea about the inner workings of these things, but it seemed likely to me that a dreamhost customer is not on the level.
I really appreciate the replies from everyone. It’s amazing all of the things that DH offers, I hope I don’t bring about my own demise in trying to make use of them : ) and very glad to know people are around to help, thanks.