たぶんこれで行けると思います。
@errmail = ('yahoo.com','yahoo.ck'); #ここで禁止メアドを指定
sub decode {
if ($ENV{'REQUEST_METHOD'} eq "POST") {
read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});
} else { $buffer = $ENV{'QUERY_STRING'}; }
@pairs = split(/&/,$buffer);
foreach $pair (@pairs) {
($name, $value) = split(/=/, $pair);
$value =~ tr/+/ /;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
foreach ( @errmail ) {
if ($value =~ /([^\x81-\xFF\s\"\'\(\)\<\>\\\`\[\{\]\}\|]+)\@([^\x81-\xFF\s\"\'\(\)\<\>\\\`\[\{\]\}\|]+)\.([^\x81-\xFF\s\"\'\(\)\<\>\\\`\[\{\]\}\|]+)/i) {
print <<"EOM";
<html>
<head>
<title>Error</title>
</head>
<body>
<center>このメールアドレスは使えません</center>
</body>
</html>
EOM
}
}
$value =~ s/</</g;
$value =~ s/>/>/g;
$value =~ s/\n|\r\n|\r/<br>/g;
$value =~ s/,/,/g;
$buffer =~ tr/+/ /;
$buffer =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
&jcode'convert( *value, 'sjis' );
$FORM{$name} .= $value;
}
}