yo utilizo estos $headers:
Código PHP:
$headers = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-type: text/html; charset=UTF-8' . "\r\n";
// Additional headers
$headers .= 'To: '.$tousername.' <'.$tomail.'>' . "\r\n";
$headers .= 'From: Notifiaciones keepyourlinks <[email protected]>' . "\r\n";
$headers .= 'Bcc: [email protected]' . "\r\n";