use HTTP::Request::Common qw(POST);
use LWP::UserAgent;

$ua = LWP::UserAgent->new();
my $req = POST 'http://www.mail.com/scripts/common/proxy.main', [
   action => 'login',
   show_frame => 'Enter',
   mail_language => 'us',
   login => 'full@email.address',
   password => 'yourpassword',
];
$content = $ua->request($req)->as_string;

if ($content =~/You Have New Mail/i) {
   send_an_email()
}