Cody is notified by blacklist.org that his site has been reported as a spam
relay, due to his SMTP Server being unprotected. Cody decides to implement an SMTP Security Server, to prevent the server from being a spam relay. Which of the following is the most efficient configuration method?

A.
Configure the SMTP Security Server to perform MX resolving.

B.
Configure the SMTP Security Server to perform filtering, based on IP address and SMTP protocols.

C.
Configure the SMTP Security Server to work with an OPSEC based product, for content checking.

D.
Configure the SMTP Security Server to apply a generic "from" address to all outgoing mail.

E.
Configure the SMTP Security Server to allow only mail to or from names, within Cody’s corporate domain.