Well, Eric mentions the problem of multiple 'Received' headers, which is
true.  If they were all packed into distribution format, there would be
many header lines; but why not compromise?  Any consolidation you can do
on the mailer entries will reduce network load.  Recall the 'exit type'
as declared by mailer:
    Type 1 (DEFRT ) makes 1 copy per recipient...
    Type 2 (BITNET) makes 1 copy per node...
    Type 3 (BSMTP ) makes 1 copy per destination mailer
 
Thus, if you have multiple nodes at your site (as most sites do) you
should point ALL your :mailer tags to the primary mailer.  With this
minimum of effort you can condense multiple-recipient mail within your
site to one copy, and it works fine with MG MODULE, provided you have
the appropriate MAILLCL file.
 
Beyond that would require custom profiles.  If there was some simple
means of just consolidating Bitnet<->EARN and Bitnet<->NetNorth traffic
it would reduce the critical links between them.  This would involve
pointing all NetNorth nodes to CANADA01 on the Bitnet side, and so forth.
This is probably too involved and complicated for a quick solution, but
worth consideration, especially as it is in line with domain addressing.
 
But you can consolidate your site mail NOW.  And it is SIMPLE. And above
all, it works.
 
<Jeff>
******************************
*  Cardinal Rule of Management, Number 3:
*    Walk softly, or your employees will hear you coming.
*  (National Lampoon, April 1987)
******************************