magento order confirmation email is not sent

Just do a small change in order.php (public_html/app/code/core/Mage/Sales/Model/Order.php)

From

$mailer->setQueue($emailQueue)->send();
To

$mailer->send();

2nd way to fix the email sending issues if the first one didn't worked.

If the email is still not sending then kindly use this change this code, it will work as well.

Copy: app/code/core/Mage/Sales/Model/Order.php

Into: app/code/local/Mage/Sales/Model/Order.php

on line 1275 (Magento 1.9.0.1), comment out return $this;

if ($this->getEmailSent()) {
    //return $this;
}