This reminds me of something that happened at the firm where I used to
work, way back in the early '90's when we first got e-mail (yes, we used to
practice without it).  A hapless associate sent a "joke" e-mail to a friend
that read "F*** YOU", with all the letters filled in.  Not only did he hit
a "reply all" function, but he did it in such a way that it popped up in a
box in the center of every user's screen with his full name in the "from"
field.  The senior partners, needless to say, were not amused.  But the guy
did eventually make partner.

All of this seems to me to fall under "caveat user."  It's an Internet
listserv; send nothing over it you wouldn't want anyone to find on Google.
We all work at schools with websites and it's easy to find someone's
personal school email if you need to reply privately and
quasi-confidentially.