If you operate a mail server, you should be aware of its “reputation,” because a bad reputation can give you issues sending email to certain recipients.

Microsoft operate a set of services called “Smart Network Data Services (SNDS)” to protect their own email services. If they see spam or other “malicious” activity from your address space, they might put you on a blacklist, and based on that reject email from you. It is easy to register yourself so that you can query the status of your IP address space. Just visit the above site and get started.

I created a quick’n’dirty monitoring script for Nagios to monitor the status of my IP address space in SNDS. Whenever there is data for one of my IP addresses, this script will return a WARNING status, so that I can look into it.

The script looks like follows:

#!/bin/bash

URL='https://postmaster.live.com/snds/ipStatus.aspx?key=12345678-1234-1234-1234-0123456789ab'

content="$(curl -s $URL)"
size=${#content}

if [ $size -gt 0 ]; then
    echo "WARNING:SNDS status seems to be UNHEALTHY"
    exit 1
fi

echo "OK:SNDS status is OK"
exit 0

You also need command and service definitions in Nagios as follows:

define command{
        command_name    check_snds
        command_line    /usr/local/lib/nagios/plugins/check_snds
}

define service {
        host_name                       my_host
        service_description             SNDS
        check_command                   check_snds
        use                             generic-service-internal
        notification_interval           0 ; set > 0 if you want to be renotified
}

Now, Nagios will monitor the “reputation” of your address space for you.