Newsletter send limit

[vishy93]

I am currently midst sending a newsletter to 12782 subscribers, it has been going since 3:00am this morning and now it is 22:41, but has only sent 4740 emails.

Investigating further it has come to my attention that the rate has been limited to 20 here:

 public function scheduledSend($schedule)
{
    $countOfQueue  = 3;
    $countOfSubscritions = 20;

    /** @var Mage_Newsletter_Model_Resource_Queue_Collection $collection */
    $collection = Mage::getModel('newsletter/queue')->getCollection()
        ->setPageSize($countOfQueue)
        ->setCurPage(1)
        ->addOnlyForSendingFilter()
        ->load();

     $collection->walk('sendPerSubscriber', array($countOfSubscritions));
}

In app\code\core\Mage\Newsletter\Model\Observer.php

Would this not be a setting configurable with smtp pro ?

I have my smtp settings as such: