This is a dumb brute-force parser for the output of mailq. If you just want to get the messages from MAILER-DAEMON you can check $entry->{from} when you are iterating over @entries:

my $header = 1;
my @entries;
my $entry = {};
while(<>)
{
   if ($header)
   {
      $header = 0 if /^--/;
      next;
    }
    if (/^(\S+)\s+(\d+)\s+(.+?)\s+<?(\S+)>?/)
    {
       push @entries, $entry if exists $entry->{msg_id};
       $entry = {};
       $entry->{msg_id} = $1;
       $entry->{size}  = $2;
       $msg->{date} = $3;
       $msg->{from} = $4;
    }
    elsif (/\s+\((.*)\)/)
    {
      $entry->{message} = $1;
    }
    elsif ( /\s+<(.*)>?/ )
    {
       $entry->{recipients} = [] unless exists $entry->{recipients};
       push @{$entry->{recipients}}, $1;
    }
}
 
push @entries, $entry if exists $entry->{msg_id};
 
foreach $entry ( @entries )
{
    print $entry->{msg_id}, join " ", @{$entry->{recipients}},"\n";
}
[download]

/J\