nd what does it have
to do with "spam"?
In the early days of the Internet, it was literally possible to know
not only the name and address of every single mail server on the Net,
but also every person using those servers. The Net was a relatively closed
community whose members had a level of trust in each other that extended
down to the computers attached to the network. To facilitate the flow
of e-mail traffic around bottlenecks, the original e-mail specifications
- which are essentially still in use, unchanged - provided for mail servers
to "trust" each other enough that Server A would "relay"
mail from Server B that was addressed to Server C in the event that the
most direct path from B to C (say, through D or E) was slow or unavailable.
As more and more people began using the Internet, this sort of trust
relationship became unworkable and, more to the point, dangerous, as it
allowed e-mail tricksters to more easily "hide their tracks".
Security-conscious system administrators began turning off the "relay"
function, and it is now standard practice not to allow a mail host to
act as a relay, or to severely restrict the instances where relaying is allowed.
In recent years, particularly with the popularity of operating systems
like linux that usually include capability to be set up as a mail server,
more and more mail servers are coming online. The problem is that in some
cases, the "relay" function is enabled by default, and the people
setting up the server aren't experienced enough to know and understand
the ramifications. Or, in some cases, the setup routine asks "Do
you want to allow this to act as a mail relay?" and the installer
will answer "yes", again without understanding what it really
Today, however, what happens much more frequently is that virus writers include a "feature" that turns a newly-infected computer into an open e-mail relay (in addition to all the other bad things it does - yet another reason to install and use anti-virus software) which spammers will actually pay to use to "funnel" spam messages.
An open mail relay is pure gold to a spammer, and they scan for them
constantly. If they find enough of them, they can pour millions of spam
messages through what is, essentially, an untraceable network. Open relays
are a major link in the "Spam Road".
When an open mail e-mail relay is found at Penn, Information Security
will request that the owner or administrator close the relay or take the
server off the network until the relay has been closed. If the owner or
administrator cannot be located, or refuses to close the relay, Information
Security will request a port disconnection under the Disconnect Policy.
OK, I'm running an e-mail server - how can I find
out if I have an open relay?
Visit the SpamHelp site at http://www.spamhelp.org/shopenrelay/,
where you can test your system, plus read a whole lot more about open
Last updated: Friday, April 23, 2010