<p>I'd like to receive error logs via email. For example, if a <code>Warning-level</code> error message should occur, I'd like to get an email about it.</p>

<p>How can I get that working in CodeIgniter?</p>

You could extend the Exception core class to do it.
Might have to adjust the reference to CI's email class, not sure if you can instantiate it from a library like this. I don't use CI's email class myself, I've been using the Swift Mailer library. But this should get you on the right path.
Make a file MY_Exceptions.php and place it in /application/libraries/ (Or in /application/core/ for CI 2)
```
```
class MY_Exceptions extends CI_Exceptions {

    function __construct()
    {
        parent::__construct();
    }

    function log_exception($severity, $message, $filepath, $line)

    {   
        if (ENVIRONMENT === 'production') {
            $ci =& get_instance();

            $ci->load->library('email');
            $ci->email->from('your@example.com', 'Your Name');
            $ci->email->to('someone@example.com');
            $ci->email->cc('another@another-example.com');
            $ci->email->bcc('them@their-example.com');
            $ci->email->subject('error');
            $ci->email->message('Severity: '.$severity.'  --> '.$message. ' '.$filepath.' '.$line);
            $ci->email->send();
        }

        parent::log_exception($severity, $message, $filepath, $line);
    }

}
```
```