[eluser]JoostV[/eluser]
You have either loaded the email library like so
Code:
$this->load->library('email', $config);
or called
Code:
$this->email->initialize($config);
$config needs to be an array of on or more options to be set, for instance
Code:
$config = array('mailtype' => 'html');
Judging from the error you are passing a string, not an array.
Options that can be set in $config can be found in the user guide.