use CGI::Carp qw(set_die_handler);
BEGIN {
    sub handle_errors {
        return if $^S;

        my $msg = shift;        
        print CGI::header();
        print 'Software error:<br/>';
        print $msg;

        # send mail
        use Mail::Sendmail;
        # ...........
        }

    }
    set_die_handler(\&handle_errors);
}