use Time::Local;
my $date = ' 19990230'; # 30th Feb 1999
$date =~ s/\s+$//;
$date =~ s/^\s*//;
my ($year, $month, $day) = unpack "A4 A2 A2", $date;
eval{ 
    timelocal(0,0,0,$day, $month-1, $year); # dies in case of bad date 
    1;
} or print "Bad date: $@";