Problem slanja maila na Yahoo i Hotmail

` global $wpdb;
$mail_new_term = $wpdb->get_results(“SELECT email FROM players WHERE active = 1”);
foreach ( $mail_new_term as $val) {
$to = $val->email;
}
$subject = ‘Predmet’;
$message = ‘Poruka’;
$from = “Admin”;
$headers = “From:” . $from;

    if (mail($to, $subject, $message, $headers)) {
        echo 'Mail poslan';
        }
    else {
        echo 'Dogodila se greška'
    }
    }
}`

Piše Mail je poslan, mail vidljiv na gmailu, a na yahoo i hotmailu ga nema. Kao poslan ali ne pronalazim ga. Čak ni u spamu.
U čemu je problem?

Nisam siguran bas za yahoo i hotmail. Mozda imaju neke grdje filtere za non-provider domains,
ali ovaj dio

nije u redu. Trebalo bi:

foreach ( $mail_new_term as $val)
{
    $to[] = $val->email;
}
$mail_list = implode(',', $to);
//$to = $mail_list;