#!/usr/bin/perl
use strict;
use warnings;
use Regexp::Common qw(Email::Address);
use Email::Address;

my $filename = 'file_to_parse.dat';

open my $rh, '<', $filename or die "$filename: $!";

# Requirement: href=, mailto: and the mailaddress must be in the same line!

my @addresses = 
  map { m/mailto:($RE{Email}{Address})/o; $1 } 
  grep { m/href=.+?mailto:/ } 
  <$rh>
;

close $rh;

{
  local $, = local $\ = "\n";
  print @addresses;
}

__END__