grep -v '@bad.com' inputfile > outputfile

findstr /v "@bad.com" inputfile > outputfile

use Email::Address;

my $data = 'this person email is hacker@bad.com
blah blah hacker@good.com blah blah
another@bad.com
';

my @emails      = Email::Address->parse( $data );
my @good_emails = grep { $_->host ne 'bad.com' } @emails;

say "@emails";       # => hacker@bad.com hacker@good.com another@bad.com
say "@good_emails";  # => hacker@good.com

$badDomain = "bad.com";
while(<>)
{
        s{s+$}{};
        print "$_n" if(!/@$badDomain$/);
}

my $bad_addresses = {'bad.com'=>1};

while (my $s = <>) {
    print $s unless (is_bad_address($s));
}

sub is_bad_address {
    my ($addr) = @_;
    if ($addr=~/^([^@]+)@([^@nr]+)$/o) {
        my $domain = lc($2);
        return 0 unless (defined $bad_addresses->{$domain});
        return $bad_addresses->{$domain};
    }
    return 1;
}

use strict;
use warnings;

my @re = map { qr/@(.*.)*Q$_E$/ } qw(bad.com mean.com);

while (my $line = <DATA>) {
    chomp $line;
    if (grep { $line =~ /$_/ } @re) {
        print "Rejected: $linen";
    } else {
        print "Allowed: $linen";
    }
}

__DATA__
good@good.com
bad@bad.com
notbad@bad.comm.com
alsobad@bad.com
othergood@good.com
not@mean.com
good@reallymean.com
bad@really.mean.com

perl -ne 'print if !/@bad.com/' file

awk '!/@bad.com/' file

my @array = <>;

 foreach(@array) {
   if(!/@bad.com$/) {
     print $_;
   }
 }