I signed off of the list for the meeting trip as well.  I did it with a
traditional email command to the list computer. But I was looking at the
archives and saw I could sign up from there by selecting one of the icons on
the menu in the GNSI archive. This looks like a great way to manage the
account.  It has a bunch of delivery option, including a suspend delivery
option!  If this is what you tried and it is not working, then get Lana, but
if you have not, check out the icon bar (on navigator-Mac the meaning of the
icons appears in the status bar at the window bottom) and open or reactivate
a new account that way.