Hi everybody,

Currently I able to use Postfix to restrict sender to send out mail to internet by mail client(outlook). But i unable to restrict SquirrelMail send mail to internet. Anybody can help me to restrict SquirrelMail send mail to internet?

Postfix to restrict sender - something like :
smtpd_recipient_restrictions =
check_sender_access hash:/etc/postfix/sender_access,
reject_unauth_destinations

smtpd_restriction_classes = local_only
local_only = check_recipient_access hash:/etc/postfix/local_domains,
reject

Any Ideas ?

It looks fine. If the squireelMail is configured to send the mail over your server using SMTP, it has to work.

config.php:

$useSendmail = false;
$smtpServerAddress = 'localhost'; // or your server name or IP
$smtpPort = 25;
$encode_header_key = '';
$sendmail_path = '';
$sendmail_args = '';
$smtp_auth_mech = 'login';
$smtp_sitewide_user = '';
$smtp_sitewide_pass = '';