here's a little script that does just that.

my $dhcplog = '/var/log/dhcpd';
my $lastfile = '/var/run/statdhcpcron.last';
my $logfile;

open $logfile, '<', $dhcplog;

sub setlast {
        my $last = shift;
        my $f;
        open $f, '>', $lastfile or return;
        print $f $last,$/;                   # last is first line
        report($f);                          # report is the rest of f
+ile
        close $f;
}

sub getlast {
        local @ARGV = $lastfile;
        my $l = <>;                          # last is first line
        $l ||= 0;                            # or start from beginning
        $l = 0 if $l > -s $logfile;          # handle rotate/truncate 
        return $l;
}

my $last = getlast();
seek $logfile, $last, 0;

while (<$logfile>) {
 # process lines
}
setlast(tell $logfile);     # remember where we stopped
close $logfile;

# mail report if needed
exit;
        
sub report {
  # returns report based on lines processed
}
[download]

don't forget to handle cases such as 'first time run' and 'file mysteriously shrunk'. this script keeps the last byte processed (and a copy of the report) in a file in /var/run.