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The Real Cause of SPAM - Open SMTP Relays
By Stephen Bucaro
Email is transported across the Internet via Simple Mail
Transfer Protocol (SMTP). SMTP relays email from server to
server in route to your mailbox. When email arrives at
your ISP's server, it is stored there until you download
it via Post Office Protocol (POP3).
Smart businesses relay email only between SMTP servers
within their company's domain. Email from outside the
domain can be deposited in your mailbox. But email from
outside the domain, that is not addressed to a mailbox
within the domain, is bounced back to the originating
domain with a Nondelivery Receipt (NDR).
Unfortunately, there are many incompetent system
administrators that have configured their SMTP servers to
relay email for everyone, not just those in the local
domain. Spammers use these open relays on the Internet to
send millions of unsolicited messages.
Stopping SPAM is not difficult. If every system
administrator configured their SMTP servers routing
restrictions to not relay email for everyone, spammers
would not be able to steal server resources that we all
pay for. These inept system administrators should learn
how to specify which domains they will allow to relay
messages through their servers.
They should not relay messages that originated from open
relay SMTP servers. There are several services that
maintain lists of open relays on the Internet.
Www.ordb.org Open Relay Database
www.mail-abuse.org Mail Abuse Prevention System
http://relays.osirusoft.com Osirusoft
Osirusoft has a link that enables you to test your email
server to see if it is open relay.
An administrator can configure their SMTP servers to
check one of these lists and reject messages from domains
on the list. They should also configure their SMTP
servers to accept messages only from connections that
authenticate first. Authentication requires the
originating server to provide a security certificate
which verifies the servers identity.
SPAM can be eradicated today if the incompetent system
administrators that have their SMTP servers configured
as open relays would learn how to specify which domains
they will allow to relay messages through their servers.
They should not be relaying messages that originated from
servers on the open relay list.
Resource Box:
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