Losing Messages

[mlevi @ idcresearch . com]

     We're running 1.93.  It appears that sometimes when a message is sent 
     to a list it is not distributed to all members of the list.  This 
     seems to be the case even when all bounces are accounted for.
     
     Can anyone suggest where we might start looking for the problem?
     
     Thanks,
     
     Mike Levi