Did some additional checking on my end, no indications of problems on this 
end...
various csh things I've done to organize info from the listserve...
foreach XX (`cat slug-address-list`)
echo $XX; grep $XX /var/log/maillog | wc -l
end
to show how many inbound/outbout mails listed in the current maillog involved 
a particular address... For people just on the slug list aproximately 130 
since the 17th.  Slightly higher for those on multiple slug related lists.  
This would indicate that the server is only sending mail once to each 
recipient.
Robert has been good enough to double check headers on his duplicated mail 
and sees that the headers are identical for each of the hops.
cat slug | awk -F@ '{ print $2 }' | sort | uniq -c | sort -r 
to give me a list of  the number addresses in the same domain;
     49 tampabay.rr.com
     15 yahoo.com
     11 gte.net
      7 hotmail.com
      5 verizon.net
      5 earthlink.net
      4 aol.com
      3 mindspring.com
      3 home.com
I was thinking this might have something to do with it, since sendmail tends 
to send bulk mail to a site a particular domain with multiple local 
recipients listed in one mail, perhaps the MTA (mail transport agent) at 
these sites have a problem, though this is something MTA's are supposed to be 
able to handle. The problem with this theory is Glen (who has a tampabay RR 
address) already stated he gets no duplicates...
I any case I'll see if I can toggle this behavior off.  
This archive was generated by hypermail 2.1.3 : Fri Aug 01 2014 - 19:37:43 EDT