We've just recently been considering how to do "one-shot" distribution also.
 
One reason _not_ to use a DIST job would be that a DIST job necessarily
creates a separate outbound mail message for each recipient (since each
gets a personalized To: line), where use of a real list might create as
few as one single copy with multiple recipients in the SMTP envelope.
The effect on your local system can be considerably different; the effect
may lessen for outlying systems, depending on distribution patterns.
(Even with batching, our student system administrators complain when some
office sends to the list of all sophomores.)
 
Mark R. Williamson
Rice University