I\'ve recently upgraded to Magento CE 1.9.1.0 and our order confirmation emails are not being sent to customers or the employees here that are setup to receive notifications
Quick solution is:
Go to the following location: /app/code/core/Mage/Core/Model/Email/Template.php
Change Line 407
if ($this->hasQueue() && $this->getQueue() instanceof Mage_Core_Model_Email_Queue) {
To:
if (!($this->hasQueue() && $this->getQueue() instanceof Mage_Core_Model_Email_Queue)) {
It will work.
Thanks Pankaj