I would use something like:

   use warnings 'all';
   use strict;
   use Email::Valid::Loose;
   use Net::DNS;
   use Fcntl qw /:flock :seek/;

   ... setup stuff ...

   sub check_addresses;

   open my $bad  => "> badmails"  or die "Failed to open badmails: $!\
+n";
   open my $good => "> goodmails" or die "Failed to open goodmails: $!
+\n";
   
   my $chunk_size = int (@adds / 20) + 1;
   
   while (@adds) {
       my @chunk = splice @chunks, 0, $chunk_size;

       my $pid = fork;
       die "Failed to fork: $!\n" unless defined $pid;
       
       unless ($pid) {
           check_addresss @chunk;
           exit;
       }
   }
     
   1 until wait () == -1;  # Wait till all children have died.
   exit;

   sub check_addr {
       my $address = shift;
       ... do some test, return 1 if good, 0 if bad ...
   }
   
   sub check_addresses {
       foreach my $address (@addresses) {
           my $handle = check_addr ($address) ? $good : $bad;
           flock $handle, LOCK_EX or die "Flock failed: $!\n";
           seek  $handle, SEEK_END, 0 or die "Seek failed: $!\n";
           print $handle, "$address\n";
           flock $handle, LOCK_UN or die "Flock failed: $!\n";
       }
   }
[download]

Abigail

I believe you. Clinging to the hope that some of my code is good I tried this using some of your suggestions:

#!/usr/bin/perl -w

#checks for valid email address
#usage validemail <file containing email addresses>

use warnings;
use strict;
use Email::Valid::Loose;
use Net::DNS;
use Parallel::ForkManager;
use Fcntl qw/:flock :seek/;

my $pm=new Parallel::ForkManager(20);
my $resolver=Net::DNS::Resolver->new();
my $addrfile = $ARGV[0];
my ($is_valid, $host, $x, @mx, $add, @adds, $handle);

#custom words that make emails invalid to you
my @custom = qw(
 postmaster
 webmaster
);
  

open (EMAILS, "$addrfile");

 while (<EMAILS>){
 $_ =~ s/\015//;
 chomp $_;
    push @adds, $_;
}
close (EMAILS);

#warning, I will delete existing files
open (BADADDR, ">badmails") || die;
open (GOODADDR, ">goodmails") || die;

foreach $add (@adds){ 
    
    $pm->start and next;

    foreach $x (@custom){
            if ($add =~ m/$x/){
                writebad(); #address is bad
                $pm->finish;
            }
        }

        #if email is invalid move on
        if (!defined(Email::Valid::Loose->address($add))){
            writebad(); #address is bad
            $pm->finish;
        }

        #if email is valid get domain name 
        $is_valid = Email::Valid::Loose->address($add);
        if ($is_valid =~ m/\@(.*)$/) {
            $host = $1;
        }
        $is_valid="";
        
        # perform dsn lookup to check domain
        @mx=mx($resolver, $host);

        if (@mx) {
            writegood(); #address is good
            }else{
            writebad(); #address is bad
        }
       
    $pm->finish;
}

close (GOODADDR);
close (BADADDR);

1 until wait () == -1;  # Wait till all children have died.
exit;

sub writegood{
    flock GOODADDR, LOCK_EX or die "Flock failed: $!\n";
    seek GOODADDR, SEEK_END, 0 or die "Seek failed: $!\n";
    print GOODADDR "$add\n";
    flock GOODADDR, LOCK_UN or die "unFlock failed: $!\n";
}

sub writebad{
    flock BADADDR, LOCK_EX or die "Flock failed: $!\n";
    seek BADADDR, SEEK_END, 0 or die "Seek failed: $!\n";
    print BADADDR "$add\n";
    flock BADADDR, LOCK_UN or die "unFlock failed: $!\n";
}
[download]

Alas, now only a couple of blank lines are written to goodmails and badmails. Fork Me!

Neil Watson
watson-wilson.ca