Where to start:
One of the best places to start looking for info on
open relays is ORBB.org, the open relay database. They also have
a service where you can test a server for open relays: http://www.ordb.org/submit/
Direct from the government, the FTC 's info page called:
Open Relays — Close the Door on Spam
Do you manage an Internet mail server? Is your server
secure? Or is it vulnerable to third-party relay? If so, then it's only a
matter of time before spammers hijack your mail server. The threat is
real, and the problem is happening now. Most modern mailers have
the capability to fight these intruders. Act now to secure your mail
server.
 An open
relay (sometimes called an insecure relay or a third-party
relay) is an SMTP e-mail server that allows third-party relay of e-mail messages.
By processing mail that is neither for nor from a local user, an open
relay makes it possible for an unscrupulous sender to route large volumes
of spam. In effect, the owner of the server -- who is
typically unaware of the problem -- donates network and computer resources
to the sender's purpose. In addition to the financial costs incurred when
a spammer hijacks a server, an organization may also suffer system
crashes, equipment damage, and loss of business. In the past, open relays were used intentionally to facilitate mail
relay between the separate closed e-mail systems (such as UUCP or FidoNet) served by the Internet. However, the Internet
has expanded enormously since then, and the potential for abuse has
expanded accordingly. Open relays are sometimes used legitimately: they
are frequently used to support mobile users connecting to a corporate
network through an ISP or to support multiple domains within an
organization, and are sometimes used for debugging connectivity or to circumvent a known routing
problem. However, other mechanisms can be used to route an authorized user
around a closed relay.
The Mail Abuse Prevention System (MAPS) is one of several organizations
that seeks to control the problem of open relays, though educating the
public about the danger, and through publishing a blacklist of
organizations whose mail hosts allow third-party relays (a similar
organization, ORBS, is now defunct). The relay feature is a part of
all SMTP-based servers, which means that most modern e-mail servers, if
unprotected, are vulnerable. According to MAPS, because spammers use
automated tools to search the Internet for vulnerable servers, an open
relay will eventually be found and used. To avoid allowing spammers free
access to their resources -- and to help stem the Internet's flow of spam
-- MAPS urges administrators to turn off the relay option on their
servers.
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| Tech Target info Last updated on: Nov 03,
2003 |
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