Open Relays and SPAM

Open Relays and SPAM
	Chapter 6. Electronic Mail

This brings us onto the subject of open relays. In the past, SMTP servers were open in that they permitted anybody, whether internally or externally, to send email through them. This made life easier for users since they could simply send email using any SMTP server.

That all changed with the rise of the scourge of the Internet " SPAM!^[4]

The definition of spam is that it is unsolicited email - pretty much the equivalent of junk mail in your post box.

People abusing the use of the Internet generate Spam in large volumes. They will often use an SMTP server that is "open" to the public to relay their messages to multiple recipients - hence the term "open relay". When they do this, the recipients will receive email's from the spammer without a request for such email.

There are problems with spam.

Firstly, it clogs up valuable bandwidth with meaningless rubbish.
Secondly, and probably more detrimental to the "open relay", is the fact that this relay ends up being added to a "blacklist" of servers. Therefore, any "valid" email sent from the open relay, will be bounced by the recipient who will be protecting themselves from spammers. The fact that your email's are valid since they originate from people within your organization is immaterial - as far as the recipient mail server is concerned, you are one of the spammers. It can take anywhere between 24 and 72 hours (and sometimes even longer) to get your mail server removed from the blacklist. During this time however, any valid email's sent by your mail server will be rejected (bounced) back to your mail server. This can be frustrating and cause a loss of productivity, but will be a real source of embarrassment to the system administrator!
Finally, spam is just plain irritating.

^[4]Search Google for the origin of the word SPAM. You will see that these UNIX/Linux people do enjoy a good laugh


Exchanging email's		Retrieving email