According to your  list header, you don't  have Send= Editor,Hold,Confirm
. Not having that little  ",Confirm" on the end--as documented--can leave
you wide  open to  loops or  spoofs. We have  been recommending  for some
time that announce-only lists be  set to Send= Editor,Hold,Confirm . This
forces mail  sent even  from an Editor  to have to  be confirmed  by that
editor before  it can be distributed.  It's a little annoying  but in the
end it can save you having this problem.

It looks  to me  like this message  actually looped back  from a  user at
HEALTHGATE.COM .  Since it had  a From: line  with your address,  it went
right through. If you'd had ",Confirm"  set on the Send= keyword it would
have come to you for approval first.

FYI this  is a  really common  occurance with remote  hosts that  use the
Microsoft  SMTPSVC  MTA,  which  probably isn't  100%  RFC  compliant.  I
suspect  the  Microsoft  product  rewrites  the RCPT  TO:  lines  in  the
envelope, but it's hard to say since we don't use it.

Nathan