My question is this: If you run a company and you caused this (I am in no way calling them out or anything). If you realized you just did this, how do you react? 1) Email the entire list again saying you apologize for that or 2) handle the email on a one-to-one?
EDITED: tsondermann points out they used option 1. I am not a member, so I did not know. I edited this to be more general.
I don't think there's an easy answer to this. Humor can be a double edged sword. If the recipient "gets it", you're a hit. If not, you look like an idiot. In print the risk is magnified.
I once had a vendor ask me what my 3 most important "business values" were. Aside from the fact that it was a stupid question, I knew I had to answer it to compete for the job. So I took a chance and said something like, "1-Quality, 2-Ethics, and 3-Taking the customer to a Chinese buffet every Wednesday". They loved it and I got the gig. It could have easily backfired, but I was in a "what the heck" mood.
They did email the whole list immediately. I received the same exact apology email minutes after the first came out.
Despite the fact that it was clearly a (now properly formatted) form email, it was still nice to see that they had realized the mistake and quickly took action in a self-effacing manner. Good on them.
EDITED: tsondermann points out they used option 1. I am not a member, so I did not know. I edited this to be more general.