:
:  much handwaving
:
: @lists = array of arrays with each sub array containing 
:          a reduced subset of recipients
foreach my $sublist(@lists){
   my $msg=MIME::Lite->new( To => join(",",@$sublist),
                            Subject => 'Daily blast',
                            Type => 'TEXT', # or whatever
                            Data => $body # again, whatever
               );
   msg->send;   # Modify MIME::Lite->send() accrodingly
   sleep(30); # tune this accordingly
}