Antispam
Mail relaying
occurs when mail is forwarded from someone else through your mail server.
Forwarding mail through a mail server is perfectly natural as long
as either the originator of the message or the receiver is a authorized
user. If neither the sender nor the recipient of the message is a local
user, it is called third-party mail relaying.
Open relay protection
If a mail server allows third-party mail relaying from everyone,
it is known as an open relay. Such a mail server attracts spammers
as it can be used to send large amounts of junk mail under false identity.
Our appliances come with built-in open relay protection.