Magento send emails using SMTP

In order to allow magento to use SMTP instead of the usual mail function, you need to take the below steps.
- Login to magento admin and go to. System->Configuration->Advanced->System->Mail Sending Settings
- Now here set the host value to your smtp host name like
mail.domain.com

- And then the default port is 25.
- Now you need to change magento file. Do not edit the core file as you will loose your change in an upgrade.
- So copy this file app/code/core/Mage/core/Model/Email/Template.php in to your local, by creating the same folder structure.
- Enable that module.
- Then in Template.php you will have to change the getMail() function as below.

public function getMail()
    {
        if (is_null($this->_mail)) {
            /* changes begin */
           $my_smtp_host = Mage::getStoreConfig('system/smtp/host');
           $my_smtp_port = Mage::getStoreConfig('system/smtp/port');
           $config = array(
                    'port' => $my_smtp_port,
                    'auth' => 'login',
                    'username' => 'email@domain.com',
                    'password' => 'yourpassword'
                );
            $transport = new Zend_Mail_Transport_Smtp($my_smtp_host, $config);
            Zend_Mail::setDefaultTransport($transport);
            /* Changes End */
            $this->_mail = new Zend_Mail('utf-8');
        }
        return $this->_mail;
    }

- After this clear your cache.
- Now magento will be able to send emails for you.