I try to send an email by codeIgniter

I am trying to send an email using the codeigniter framework but I receive the following error.

  

A PHP Error was encountered Severity: Warning Message: fsockopen ():   unable to connect to localhost: 25 (Connection refused) Filename:   libraries / Email.php Line Number: 2061

     

Backtrace:

     

File: /var/www/html/test/application/controllers/Mantencion.php Line:   69 Function: send   File: /var/www/html/test/index.php Line: 315 Function: require_once

Here is my code.

$config = array();
            $config['useragent']           = "CodeIgniter";
            $config['mailpath']            = "/usr/sbin/sendmail"; // or "/usr/sbin/sendmail"
            $config['protocol']            = "smtp";
            $config['smtp_host']           = "localhost";
            $config['smtp_port']           = "25";
            $config['mailtype'] = 'html';
            $config['charset']  = 'utf-8';
            $config['newline']  = "\r\n";
            $config['wordwrap'] = TRUE;

            $this->load->library('email');

            $this->email->initialize($config);

            $this->email->from('[email protected]', 'admin');
            $this->email->to('[email protected]');

            $this->email->subject('Тест Email');
            $this->email->message('ASDADS');
            // $this->email->message($this->load->view('email/'.$type.'-html', $data, TRUE));

            if ($this->email->send()) {
            $this->session->set_flashdata('success_msg', '  Correo enviado exitosamente');
            }
            show_error($this->email->print_debugger());

I'm using Linux Mint. A query should I install a service to send an email?