given ($address) {
    when (@whitelist) { $score -= 30 }
    when (@blacklist) { $score += 50 }
    when (/example\.com$/) { $score = 0 }
    default { ... }
}

##</code><code>##

for my $a ($address) {
    if (grep $_ eq $a, @whitelist) { $score -= 30; last; }
    if (grep $_ eq $a, @blacklist) { $score += 50; last; }
    if ($a =~ /example\.com$/) { $score = 0; last; }
    ...
}