>How is    From:    A@B
>          From:    X@Y
 
RFC822 says  (in 4.1)  that the  meaning of  that is  "unspecified", even
though the formal definition they have  chosen allows for any field to be
specified any number of times. I personally chose to call that "illegal",
because  I can't  find  any  reasonable interpretation  and  I have  more
important uses for my time than dealing with "lost causes" of this type.
 
>Different from
>          From:    A@B, X@Y  (which is perfectly legal under RFC822) ?
 
As you said later, this is legal  ONLY if there is a 'Sender:' field, and
the 'Sender:' field  can point to only one mailbox.  LISTSERV simply does
not support  commands or notebook  database entries having more  than one
origin, anyway.
 
  Eric