customize Email template with variable : Magento

PHP file Code

function sendTestMail($emailId,$VariableName,$name)
{
        $mailer = Mage::getModel('core/email_template_mailer');
        $emailInfo = Mage::getModel('core/email_info');
        $emailInfo->addTo($emailId, $name);
        if ($copyTo && $copyMethod == 'bcc') {
            // Add bcc to customer email
            foreach ($copyTo as $email) {
                $emailInfo->addBcc($email);
            }
        }
        $mailer->addEmailInfo($emailInfo);

        // Email copies are sent as separated emails if their copy method is 'copy'
        if ($copyTo && $copyMethod == 'copy') {
            foreach ($copyTo as $email) {
                $emailInfo = Mage::getModel('core/email_info');
                $emailInfo->addTo($email);
                $mailer->addEmailInfo($emailInfo);
            }
        }

        // Set all required params and send emails
        $mailer->setSender(Mage::getStoreConfig('sales_email/order/identity', $storeId));
        $mailer->setStoreId($storeId);
        $mailer->setTemplateId(1);   //"1" is email Template ID

        $mailer->setTemplateParams(array(

                'customer_name'        => $name,

                'VariableName'        => $VariableValue

            )

        );
      
        $mailer->send();
        return;
    }


Code Inside Email Template
Magento Admin >System >  Transnational Emails > Select Email Template > Template Content

- {{var VariableName}}

eg. <span>{{var VariableName}} </span>