vBulletin 4 sends an e-mail even the input e-mail syntax is not valid e-mail

[postcd]

Hello,
it appears that vBulletin 4.2.5 Alpha 2 sends an activation e-mail to newly registered user even the e-mail is wrong, like "FK@9711"
Please how to fix this inside the code?

I have found following in /includes/class_mail.php

	function send($force_send = false)
        {
                // No recipient, abort
                if (!$this->toemail)
                {
                        return false;
                }

                // Check debug settings
                if (!$force_send AND defined('DISABLE_MAIL'))
                {
                        if (is_string(DISABLE_MAIL))
                        {
                                // check for a recipient whitelist
                                if (strpos(DISABLE_MAIL, '@') !== false)
                                {
                                        // check if the address is allowed
                                        if (strpos(DISABLE_MAIL, $this->toemail) === false)
                                        {
                                                return false;
                                        }
                                }
                                else if (strpos(DISABLE_MAIL, '.log') !== false)
                                {
                                        // mail is only logged
                                        $this->log_email('DEBUG', DISABLE_MAIL);

                                        return true;
                                }
                                else
                                {
                                        // recipient not in the whitelist and not logging
                                        return false;
                                }
                        }
                        else
                        {
                                // DISABLE_MAIL defined but isn't a string so just disable
                                        if (strpos(DISABLE_MAIL, $this->toemail) === false)
                                        {
                                                return false;
                                        }
                                }
                                else if (strpos(DISABLE_MAIL, '.log') !== false)
                                {
                                        // mail is only logged
                                        $this->log_email('DEBUG', DISABLE_MAIL);

                                        return true;
                                }
                                else
                                {
                                        // recipient not in the whitelist and not logging
                                        return false;
                                }
                        }
                        else
                        {
                                // DISABLE_MAIL defined but isn't a string so just disable
                                return false;
                        }
                }

                // Send the mail
                return $this->exec_send();
        }

Maybe it is correct code to modify?

Here they mention following:

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // invalid emailaddress
}

if (!checkdnsrr($domain, 'MX')) {
    // domain is not valid
}

MX code may delay things so is questionable. Maybe better to validate on registration form?

/register.php contains:

        // check for matching email addresses
        if ($vbulletin->GPC['email'] != $vbulletin->GPC['emailconfirm'])
        {
                $userdata->error('emailmismatch');
        }

can i append after that:

        // check for valid email addresses
        if (!filter_var($vbulletin->GPC['email'], FILTER_VALIDATE_EMAIL))
        {
                $userdata->error('to be valid e-mail');
        }

When i do it, reg. form says "Could not find phrase 'to be valid e-mail'."
After using valid e-mail then no warning appear. Is this sufficing, or do You have idea how to fix it please?