Sending email to gmail (Codeigniter), appears as spammer

I have a problem sending emails to GMail via CodeIgniter. All the emails I send do not appear in the images and are left with a message from GMail saying it could be a spammer . Is there any way to overcome this?

Here is a print of how the email appears in gmail:

Somethinglikethisshouldappear(thefollowingimageisasitappearsinthewebmailservice):

Codeused:

$this->load->model('template_model');$mensagem=$this->template_model->addUtilizador($assunto,$msg);$config=array('protocol'=>'smtp','smtp_host'=>'ssl://*********','smtp_user'=>'*****@*****.com','smtp_pass'=>'********','smtp_port'=>465,'validate'=>TRUE,'charset'=>'utf-8','mailtype'=>'html','useragent'=>'CentrodeEventos','wordwrap'=>true,'priority'=>1);$this->load->library('email',$config);$this->email->set_mailtype("html");
            $this->email->from('[email protected]', 'Centro de Eventos FEUP');
            $this->email->to($destinatarios);
            $this->email->subject($assunto);
            $this->email->message($mensagem);
            $this->email->send()