SMTP Settings

Block outgoing SMTP - SMTP_BLOCK
Block outgoing SMTP except for root, qmail/postfix and mailman. This forces scripts/users to use the qmail/postfix binary instead of sockets access. This option requires the iptables ipt_owner/xt_owner module to be loaded.
Default: 0 Range: 0-1

Allow local connections - SMTP_ALLOWLOCAL
Allow outgoing SMTP connections to the loopback device on port 25 (If SMTP_BLOCK is enabled).
Default: 1 Range: 0-1

SMTP ports to block. You should list all ports that qmail/postfix is configured to listen on.
Default: 25,465,587

Redirect outgoing SMTP connections destined for remote servers for non-bypass users to the local SMTP server to force local relaying of email. Such email may require authentication (SMTP AUTH). Default: 25,465,587

SMTP allowed users - SMTP_ALLOWUSER
Allow the following comma separated users to bypass SMTP_BLOCK. Note: root user is always allowed.
Default: qmaild,qmaill,qmailp,qmailq,qmailr,qmails,postfix

SMTP allowed groups - SMTP_ALLOWGROUP
Allow the following comma separated groups to bypass SMTP_BLOCK. Note: root group is always allowed.
Default: qmail,nofiles,postfix,postdrop,mail,mailman