code: public function fetchEmails()
    {
      $this->fetchedEmails = array();
  
      try
      {
        $response = $this->sendRequest('GET', "/api/v1/inboxes/{$this->config['inbox_id']}/messages");
        $this->fetchedEmails = json_decode($response->getBody());
      }
      catch(Exception $e)
      {
        $this->fail('Exception: ' . $e->getMessage());
      }
  
      $this->sortEmails($this->fetchedEmails);
  
      // by default, work on all emails
      $this->setCurrentInbox($this->fetchedEmails);
    }
docs: Fetch Emails
  
  Accessible from tests, fetches all emails