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Desktop Spam-filtering Tools

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PCQ Bureau
New Update

We've all seen spam in one form or the other. If a recent

study is to be believed, spam costs companies over $10 bn a month worldwide in

system downtime and employee time lost that could have been utilized

productively.

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While we manually handle spam using the 'delete and move

to next mail' approach,  it becomes

difficult to do so in many cases and one or more tools are often necessary to

keep this menace in check. The job of handling spam can be done either at the

server or the client end. While the former approach monitors and runs scripts on

the server for all/several mailboxes/users that can be done by the system

administrator, the latter is something that can be done by individual users for

their own mailbox.

Let's look at some desktop spam-filtering tools for how

they stack up against each other. But before that, let's understand some of

the key concepts associated with this and the various techniques that these

tools use to classify a mail as spam (or otherwise).

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How tools classify

spam

 



One way to classify mail is to have a central server to

store information about known spam sending e-mail/IP addresses. The headers of

the mail are checked against the data obtained from this server and if it

matches, the mail is marked as spam. The server can be contacted every time the

mail is checked, else you can configure software to download information about

known offenders from the central server, say, once a week and keep a local copy

for reference-similar to the virus definitions model. These lists are called

'blacklists', wherein the software knows that the moment a match occurs with

one of these addresses, the mail can be classified as spam.

There are other software that need to be trained to

classify them as spam. To begin with, they have no blacklist to match the mail

against. You have to mark junk mail in your inbox as spam so that the software

learns and then extracts information from  such

mail-like the sender ID and IP address to add to its blacklist. You can also

tell the software explicitly what information to use from that e-mail, like

blacklist this e-mail address, this IP address and this domain.

Perhaps the

best tools are ones that combine these two, and spread what they have learnt

across the community. That is, when a person marks such a mail as junk that the

software used to identify as spam, the tool not only learns locally but also

reports back to a central server so that other users can benefit from their work

when they update their blacklists. Like blacklists, there are 'whitelists'

as well. Whitelists feature trusted senders, mail from whom is not spam. This is

people specific as your set of trusted senders is specific to you. So whitelists

need not be stored on a server or shared with others. Other methods used to

identify spam include inspecting the subject line and the body of the e-mail for

specific words (say, pharma and pills) or phrases and flagging them as spam

accordingly. Again this list can be central, local or both and, as usual, the

local list takes precedence over the central one where both exist. Some tools

also offer the facility to block all mail originating from certain countries or

top-level domains.

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Tools also differ in where they fit in during the e-mail

checking. While some require themselves to be given access to the mailbox before

you allow your e-mail client to download mail from the account, other

transparent ones run as proxy servers on the local machine. Your e-mail client

is then given the address of this proxy server which downloads e-mail from your

server, filters them, delivering the good ones to your inbox while the spam goes

to a quarantine folder or to the bin, depending upon the options offered by the

software and your preferences.

Most tools operate on POP accounts, some support IMAP while

others are capable of weeding out of spam over Web e-mail accounts like Hotmail

as well.

Here we put some of the popular spam filtering desktop

tools to test with the emphasis, obviously, being on their ability to weed out

spam from legitimate mail. Solutions that do the job out of the box have a head

start over those that start from scratch and require learning. Tools that offer

both built-in/server-based as well as local/user habits learning based filtering

score higher than those that offer only one. Flexibility is another

advantage-for example, the ability to have user rules over rides built-in

ones. Additional features like language-based filtering mean extra points. But

ultimately everything boils down to how effective the tool is in filtering out

spam with minimum of user effort after the initial training. The process

automation is the key-be it via downloading 'definitions' or filters from

a central server or by using advanced filtering algorithms-because if your

tool requires tinkering every second day then it isn't serving much of a use.

The winner here reflects that philosophy.

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yMail

 




www.spacejock.com/yMail.html


yMail is a stand-alone, portable e-mail client with integrated spam-tackling
capabilities good enough to make it one of the contenders in our shootout. The

portable bit means that you can carry it around on a USB drive as it can be

configured to store mail, contact information and the likes in the same folder

as the program files.



The e-mail capabilities are pretty basic and we think

it's more suited to an e-mail popper role to filter out spam and other

unwanted e-mail, meaning it's to be used in combination with your current

e-mail client (like Outlook or Eudora) and not necessarily as a replacement.

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yMail uses Bayesian techniques to classify spam and does a

very good job at that. It starts with a clean slate and learns what is spam and

isn't as you go along. This means that you initially have to spend some time

and effort with it, but every mail you mark as spam adds to yMail's knowledge

and increases its ability to identify junk mail accurately the next time. In our

tests when once we marked the first batch of junk mail as spam, yMail was good

enough to weed out all further junk mail on that account-and that is an

achievement good enough to make it the winner in our shootout, as far as its

spam-filtering abilities are concerned.

SpamAware



www.jam-software.com 


This tool is
very similar to SPAMfighter in terms of look, feel and functionality- infact

we had to closely re-examine the two to really appreciate the differences. For

example, its default behavior is to mark junk mail by adding a prefix 'SPAM'

to the subject, while SPAMfighter moves it to a folder it creates. Of course,

you can then create a filter in your e-mail client to move all mail with a

prefix SPAM to trash else you desire.



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Like SPAMfighter, it sits inside Outlook/Outlook Express

and automatically scans all incoming mail. Where it fails to deliver is in terms

of performance. The scanning process is a crawl compared to SPAMfighter and

doesn't offer any improvement in terms of accuracy to compensate for

that.It's a free tool and is the only one in the pack that doesn't support

custom keyword filters. It has all the regular features such as support for

whitelistas and blacklists, language-based filtering, etc. It can compare the

headers of a suspicious mail against data obtained from a central server.

PAMfighter



www.spamfighter.com

 



SPAMfighter sits inside Microsoft Outlook and Outlook
Express, and monitors incoming mail on all accounts. It compares the mail

against locally configured blacklists and whitelists as well as rules that are

periodically downloaded from a central server. Mails that are identified as spam

are moved to a separate folder within Outlook/OE, which you can browse later, if

necessary, to ensure that no useful mail was junked and/or clean the folder.


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While it doesn't support keyword-based classification of

e-mail, it does innovate in the form of language-based e-mail filtering. For

example, you can configure it to junk mail in languages other than English. It

also provides for you to report (via single click) to the central server, spam

that might have been missed by the automatic detection process.

All in all, it offers pretty good filtering capabilities at

an almost real-time speed via an interface that is easy to use, fitting in

nicely within Outlook/Outlook Express. It requires no changes in e-mail settings

or how you go about checking your mail. Thus, most people wouldn't even notice

it (apart from the good work it does), which can't be said of some of the

other tools that we've seen.

Sure it isn't of any use to those who prefer other e-mail

clients but that shouldn't take much away from the good job it does.

Mailwasher  Free/ Pro

 




www.mailwasher.net



Mailwasher is like an e-mail popper with advanced spam

filtering capabilities. You set up an e-mail account just like in an e-mail

client and it downloads the mail headers for you to preview, while marking the

spam it can identify. The free version identifies spam using built-in filters

and, of course, allows you to manually mark spam. You can then proceed to delete

these messages from server and/or send a 'bounce back' to the sender, which

looks just like the kind of error mail you get back from an invalid e-mail id.

The Pro version offers much better protection from spam by

allowing the client to maintain black and white lists as and when you mark

specific messages as spam and/or those from trusted servers. It offers access to

a global spam database and DNS spam blacklists both of which are maintained

online on central server(s) and greatly increase the effectiveness of the spam

identification process.

Once spam has been marked/bounced/learnt from, you can launch your e-mail client and

download e-mail. You can use almost every mail client. Mailwasher has a button

to launch your default mail client-a small but handy convenience.

The Pro version also supports keyword-based filters,

multiple accounts (as opposed to only one in the free version) as well as access

to IMAP, Hotmail, MSN and AOL accounts in addition to the POP accounts supported

by the free variant. It also allows you to preview a message before you decide

what to do with it in case you are not able to identify the nature of the

message just by looking at the headers.

Letterman Spam

Control Pro

 




www.whatlink.com


 



This is perhaps the

most feature rich tool amongst the ones we gave a run during the shootout. It

can operate in multiple modes-as a standalone 'popper' to filter out your

mail before download which you can use, say, at the start of the day when

you're checking mail for the first time. And for the rest of the day you can

use it as a proxy server, an intermediary between your e-mail client and server

that not only filters out spam but also blocks hostile links in other e-mail. It

does a good job of filtering mail straight out of the box using built-in rules

and allows creation of custom rules.

Letterman Spam

Control also supports filtering of Web-based e-mail accounts such as Yahoo! and

MSN/Hotmail. Blocking of mail based on their language and analysis of mail

written in languages other than English (like Chinese) is also supported. It

also provides detailed logs/reports for each message indicating the criteria

that lead to the message being marked as spam.

All this sounds

impressive but where it loses out is usability. It offers a plethora of options

but doesn't feature the most intuitive of interfaces, which means that it can

be quite intimidating to most users. We had to spend considerable time to find

where each feature option was before we could gain enough familiarity with the

tool.

Spam Filtering Tools: A Comparative
Features Mailwasher Free Mailwasher Pro SPAMfighter yMail SpamAware Letter Spam Control Pro
E-mail client Any Any Outlook/ Outlook Express Self/Any Outlook/ Outlook Express Any
Local analysis Yes Yes Yes Yes Yes Yes
Compared against a server/online updating No Yes Yes No Yes Yes
Blacklists No Yes Yes Yes Yes Yes
Whitelists No Yes Yes Yes Yes Yes
Report spam to server No No Yes Yes Yes Yes
Custom keyword filters No Yes No Yes No Yes
Language-based filtering No No Yes No Yes Yes
Price Free $37.00 Free Free Free $14.95

Kunal Dua

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