This script is Copyright (C) 1999-2017 Tenable Network Security, Inc.
An open SMTP relay is running on the remote host.
Nessus has detected that the remote SMTP server allows mail relaying.
This issue allows any spammer to use your mail server to send their
mail to the world, thus flooding your network bandwidth and possibly
getting your mail server blacklisted.
See also :
Reconfigure your SMTP server so that it cannot be used as an
indiscriminate SMTP relay. Make sure that the server uses appropriate
access controls to limit the extent to which relaying is possible.
Risk factor :
High / CVSS Base Score : 7.8
CVSS Temporal Score : 6.7
Public Exploit Available : true