SMTP settings

This script just sets a couple of SMTP parameters. Several checks need to use a third party host/domain name to work properly. The checks that rely on this are SMTP or DNS relay checks. By default, example.com is being used. However, under some circumstances, this may make leak packets from your network to this domain, thus compromising the privacy of your tests. You may want to change this value to maximize your privacy. Note that you absolutely need this option to be set to a *third party* domain. This means a domain that has *nothing to do* with the domain name of the network you are testing.