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There is two (2) major categories
of anti-spamming tools (with the mean of software):
a) anti-spam tools that are targeting
the end users of e-mail service (i.e. user-based or client-based)
and
) anti-spam tools that are installed to the e-mail servers (i.e.
server-based).
he last mentioned are installed
centralized to the e-mails servers of organizations and companies (eg.
ISP and E-mail providers), and the first ones which are the most well-known
are programs that can be installed to the end users' computers and provide
a more personal protection against spam.
A. TOOLS FOR END-USERS
Below, there is a list of the most
well known anti-spam programs.
We have to notice here that in case you are using a web interface
to deal with e-mails (i.e. web mail) like for example: Hotmail,
Yahoo!, In.gr,
Mail.gr, etc.
then unfortunately you cannot use any of the following programs,
but you may only use the supplied anti-spamming protection from
the e-mail provider (if any).
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Most of the anti-spamming programs
are installed as plug-ins to well-known e-mail clients like Microsoft
Outlook, Microsoft
Outlook Express (Free), Mozilla
Thunderbird (Free), Eudora,
etc. thus users do not have to change their favorite e-mail program for
sending and receiving e-mails. The rest of anti-spamming programs are
working independently playing the role of an intermediate filter between
end-user's e-mail client and provider's e-mail server. In this case, user
is required to setup the anti-spam program, as well as, to do some setting
into his/her e-mail client.
With respect to the methods used for
detecting spam messages those tools are using a variety of complementary
(in most cases) methods:
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Whitelists/Blacklists: is one of the most
common and easy method to use. They can be either maintained manually
by users or e-mail administrators or automatically by the anti-spam
software based for instance on users replies. Very useful in order
not to lose any message from a known source like friends and collegues.
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Realtime Blocklists: They are databases
of known spammers in the form of either IP address of their e-mail
servers to be blocked (i.e. DNSBL) or links that it is inside the
body of a spam (i.e. URIBL). Both lists are very often used by e-mail
administrators to check if an e-mail is spam in the server side. (see
also Search Engine)
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Challenge/Response: Another technique that
provides a quite safe method for end-users which is offered from some
anti-spamming software tools. The challenge process assumes that a
spammer would not be able to (or not bothers to) answer it (i.e. response).
Challenge of course is in a form that only a human sender may reply.
If no response is provided the message is marked as suspicious and
it is quarantined. Although, challenge response seems to be a very
good approach; there are a number of significant limitations, such
as the deadlock communications (i.e. when two people both challenge
response each others), and getting e-mails from mailing lists or newsletters.
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Bayesian Filtering: Is one of the most prominent
methods currently used that it is rely on adaptive filtering algorithms,
such as Bayesian filter (the word refers to the mathematician Thomas
Bayes 1702-1761). Bayesian filters are personalized to each user
and adapt automatically to changes in spam in order to determine the
likelihood that an e-mail is spam. Bayesian analysis compares the
word/phrase found into the incoming e-mails in question to the frequency
of the same word/phrase in the intended recipients previous e-mails.
These filters are regarded very powerful and of the most accurate
techniques for blocking spam, nowadays.
The following alphabetic list contains the most
well-known anti-spam tools for end-users.
You may also search for anti-spamming software into the
followings web sites: Tucows
and Download.com.
Learn more on how you will not receive spam...
B. SERVER-BASED ANTI-SPAMMING
SOLUTIONS
List in alphabetic order of Anti-spamming solutions
for companies and organizations.
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Barracuda
Spam Firewall (Hardware & Software)
The Barracuda Spam Firewall is an integrated hardware and software
solution for complete protection of your email server. It provides
a powerful, easy to use, and affordable solution to eliminating spam
and virus from your organization by providing the following protection:
Anti-spam, Anti-virus, Anti-spoofing, Anti-phishing, Anti-spyware
(Attachments), Denial of Service.
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MailScanner
(Free)
MailScanner is a highly respected open source email security system.
This technology is fast becoming the standard email solution at many
ISP sites for virus protection and spam filtering. MailScanner scans
all e-mail for viruses, spam and attacks against security vulnerabilities
and plays a major part in the security of a network.
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Mailwasher
Server (Free)
MailWasher Server is a highly accurate server-side spam filtering
package with a polished, well-integrated web interface and built-in
quarantine management facilities. Fully supports Windows Server/Exchange
Server, Linux and Solaris.
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Sender
Policy Framework (Free)
SPF fights return-path address forgery and makes it easier to identify
spoofs. Domain owners identify sending mail servers in DNS. SMTP receivers
verify the envelope sender address against this information, and can
distinguish authentic messages from forgeries before any message data
is transmitted.
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SpamAssassin
(Free)
SpamAssassin is a mature, widely-deployed open source project that
serves as a mail filter to identify Spam. SpamAssassin uses a variety
of mechanisms including header and text analysis, Bayesian filtering,
DNS blocklists, and collaborative filtering databases. SpamAssassin
runs on a server, and filters spam before it reaches your mailbox.
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SpamStats
(Free)
Spamstats analyses log entries from your postfix, exim or sendmail
email server, together with data from spamassassin, and will report
to you the amount of spam, and non spam messages, that your site receives.
Other nice and exclusive features are a sorting of top spammed email
addresses of your domain, volume informations, html output.
Useful articles for E-mail server administrators:
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