smtp: Generate SMTP messages (emails) from logs

The destination is aimed at a fully controlled local, or near-local, trusted SMTP server. The goal is to send mail to trusted recipients, through a controlled channel. It hands mails over to an SMTP server, and that is all it does, therefore the resulting solution is as reliable as sending an email in general. For example, AxoSyslog does not verify whether the recipient exists.

The smtp() driver sends email messages triggered by log messages. The smtp() driver uses SMTP, without needing external applications. You can customize the main fields of the email, add extra headers, send the email to multiple recipients, and so on.

The subject(), body(), and header() fields may include macros which get expanded in the email. For more information on available macros see Macros of AxoSyslog.

The smtp() driver has the following required parameters: host(), port(), from(), to(), subject(), and body(). For the list of available optional parameters, see smtp() destination options.

Declaration:

   smtp(host() port() from() to() subject() body() options());

Example: Using the smtp() driver

The following example defines an smtp() destination using only the required parameters.

   destination d_smtp {
        smtp(
            host("localhost")
            port(25)
            from("alert service" "[email protected]")
            to("Admin #1" "[email protected]")
            subject("[ALERT] Important log message of $LEVEL condition received from $HOST/$PROGRAM!")
            body("Hi!\nThe alerting service detected the following important log message:\n $MSG\n-- \n")
        );
    };

The following example sets some optional parameters as well.

   destination d_smtp {
        smtp(
            host("localhost")
            port(25)
            from("syslog-ng alert service" "[email protected]")
            to("Admin #1" "[email protected]")
            to("Admin #2" "[email protected]")
            cc("Admin BOSS" "[email protected]")
            bcc("Blind CC" "[email protected]")
            subject("[ALERT] Important log message of $LEVEL condition received from $HOST/$PROGRAM!")
            body("Hi!\nThe syslog-ng alerting service detected the following important log message:\n $MSG\n-- \nsyslog-ng\n")
            header("X-Program", "$PROGRAM")
            );
    };

Example: Simple email alerting with the smtp() driver

The following example sends an email alert if the eth0 network interface of the host is down.

   filter f_linkdown {
        match("eth0: link down" value("MESSAGE"));
    };
    destination d_alert {
        smtp(
            host("localhost") port(25)
            from("syslog-ng alert service" "syslog@localhost")
            reply-to("Admins" "root@localhost")
            to("Ennekem" "me@localhost")
            subject("[SYSLOG ALERT]: eth0 link down")
            body("Syslog received an alert:\n$MSG")
            );
    };
    
    log {
        source(s_local);
        filter(f_linkdown);
        destination(d_alert);
    };
smtp() destination options

Last modified October 29, 2023: Create manpages (#34) (9534f54)