sub main {
  my $input_qfn   = "input.file";
  my $pattern_qfn = "pattern.file";

  my %emailAddresses;
  {
    open(my $input_fh, '<', $input_qfn)
      or die("Can't open input file \"$input_qfn\": $!\n");

    while (<$input_fh>) {
      chomp;
      my ($userName, $emailAddress, $division, $fullName) = split /\|/;
      ++$emailAddresses{$emailAddress};
    }
  }

  open(my $pattern_fh, '<', $pattern_qfn)
    or die("Can't open pattern file \"$pattern_qfn\": $!\n");

  while (<$pattern_fh>) {
    chomp;
    if ($emailAddresses{$_}) {
      print "$_ exists in the input file\n";
    } else {
      print "$_ doesn't exist in the input file\n";
    }
  }
}