This is happning because of there is problem with mail configuration in your magento store,
so I have 2 suggestions

1. navigate to /home/easter13/public_html/app/code/core/Mage/Adminhtml/Block/Sales/Order/View.php page
at line number 92 replace your code with below code.

if ($this->_isAllowedAction('emails') && !$order->isCanceled()) {
            $confirmationMessage = $coreHelper->jsQuoteEscape(
                Mage::helper('sales')->__('Are you sure you want to send order email to customer?')
            );
            $this->addButton('send_notification', array(
                'label'     => Mage::helper('sales')->__('Send Email'),
                'onclick'   => "confirmSetLocation('{$confirmationMessage}', '{$this->getEmailUrl()}')",
            ));
        }
Then clear cache, refresh the page and check your error will gone.

2. navigate to /home/easter13/public_html/app/code/core/Mage/Adminhtml/Block/Sales/Order/View.php page
at line number 92 uncomment this code and Then clear cache,
refresh the page and check your error will gone.