I've seen that strange 'unable to post' message when what was meant was,
"this cannot be distributed to a particular person/address on the list."
 
Sooner or later, the listowner or other authority takes action.
 
Stay calm.  Walk, do not run, to your delete key. Say a quiet prayer for
whoever didn't know how to tweak the system properly.
 
It is a mere pebble in our shoe, as we march along the information
superhighway.
 
--bayla