Spam fighting apps reviewedBy Antony Sidwell. Published: 11th Jul 2003, 23:03:25 | Permalink | Printable
Battle royale!Can't escape spam? Fret no more. RISC OS has a good choice of spam busting software and Antony Sidwell's on the case with his comparative review.
"Spam is the single biggest problem society has at the moment." That's how someone with no sense of proportion might describe the endless tide of unsolicited emails being sent to most email addresses in use today. Even if you've got a less skewed outlook on the world, dealing with spam is annoying, time-consuming, and will cost you money if you're on a metered internet connection.
RISC OS users are lucky then, to have three different anti-spam packages available. These are MailScout - a commercial offering - and AntiSpam and SpamStamp, both available without charge. I tried out the demo version of MailScout and installed AntiSpam and SpamStamp to give them a full trial. I was previously using POPstar and Newsbase to download and process email.
Antispam has been designed to try and pick out unwanted emails whilst they are still on the server, so that you can delete them without having to waste your time downloading them first. You can also set it up to collect email for you (instead of using Popstar, for instance), in which case you can control whether you want to download a matched email immediately or leave it on the server. This can be handy if you have different access costs at different times of day.
AntiSpam's progress window
It works by connecting to your POP3 email account and comparing the headers of each email to various rules you've specified. A rule consists of the action to take if the email matches(e.g. Delete), the header to check (e.g. "Subject:"), and a simple piece of text to find in that header. These rules are applied in the order you arrange them in the rules file, so that you can arrange to delete all emails with "prescription" in the subject unless it was sent by a particular person, for instance.
The Stronghelp manual supplied with AntiSpam contains a clear step-by-step guide to the rules file, including how to write your own rules based on the headers of email you have received, and makes the whole process really quite straightforward. The installation instructions are similarly clear and simple - all in all you should have few problems getting the program working. If you do have any problems with it there is a smartgroup where you can ask questions and read message archives.
AntiSpam is freeware and open source, distributed under the GNU GPL, and people are actively encouraged to try and improve it.
SpamStamp uses an entirely different technique to deal with spam. It checks through all your emails after they've been downloaded and before your email program gets its hands on them. It adds an extra header to each email saying whether or not it has been identified as spam. You should then be able to use your email program to sort these into a separate folder, mark them as read or delete them as you desire.
Geeky spam stats from SpamStamp
Spamstamp needs to download the whole message because it uses the latest spam identification technique - Bayesian statistics. Essentially, this involves keeping tallies of how often a word appears in an unwanted email and how often a word appears in a valid email. It can then use this information to determine how likely it is that any particular word will appear in a real email and how likely it is to appear in a spam. By checking these chances against every word in the whole email, it arrives at a probability that the whole message is a spam.
Like AntiSpam, SpamStamp comes with a well-written Stronghelp manual giving you full instructions on how to install and use it. The installation is a little more complex, as you have to get SpamStamp to sit "between" the fetching of email and the processing by the email package, but instructions are given for installing with POPstar and Newsbase, Messenger Pro or Pluto. Instructions are not yet supplied for use with the ANT Internet suite, but Paul Vigay has a patch available for the ANT Suite which should allow SpamStamp to work with Pluto or Messenger Pro.
Ideally, you'll probably want to just filter spam emails into another folder or mark them as read rather than delting them, so that you check every so often and teach SpamStamp when it has wrongly identified something as spam.
SpamStamp is almost-freeware - you are required to send the author a short message of some kind saying that you are using it (so it'll cost you the price of a stamp, an email message, whatever) so that the author gets the satisfaction of knowing his work is useful.
MailScout has more in common with AntiSpam than SpamStamp - it too checks the headers of the email when it is still on the server to save you download time. Like AntiSpam, you set up rules by hand to catch spam based on the headers (the available fields to check are Subject, From and To), and have the option of "whitelist" rules to let mail through if it would otherwise be classed as spam.
MailScout smells spam
In addition, it has a number of "preset" filters to filter out HTML emails, emails marked as bulk and so on, which can be set on or off from a dialogue box.
After applying these filters, it opens up a list of all email in your account, and lets you decide whether or not the rules have been applied correctly before email is deleted. You can select spam that has been missed or deselect ones which you don't want deleted.
MailScout can check either POP3 or IMAP mailboxes, where AntiSpam works only with POP3. Most people have POP3 accounts, but the IMAP facility could be useful to some.
MailScout will you cost you 25UKP, though a limited demo version (it won't delete email, but you can get an idea of how it works) is available from the website.
How they all compare
AntiSpam and MailScout are pretty much direct competitors - they are trying to do the same job, they just take slightly different approaches. Neither is in direct competition with SpamStamp, because SpamStamp downloads whole emails rather than deleting the email on the server, and it can learn about spam types as it goes along rather than being configured by hand.
MailScout allows you to set up rules based on subject lines, senders and so on and then make sure you're getting all the emails through that should get through. For a once- or twice-daily collection of mail started manually, it might be worth getting so you can be sure all valid email gets through, however you can't really automate this as you might not be at the computer to confirm the emails to delete.
AntiSpam allows for more fine tuning - rather than having a blacklist and whitelist you can choose in what order different accepting and deleting rules should be applied, and you also have the full range of email headers to choose from when making rules. It doesn't ask for confirmation, it just deletes things if they are matched, but if you're careful with the rules you add, and test them before using them for real you shouldn't end up deleting genuine mail. In particular, if you use it in conjunction with SpamStamp, you can make the rules lax enough to avoid accidental deletions completely while still wiping out a large percentage of spam before it leaves the server, confident that the second line of defence can deal with any spam that gets through.
At no cost, I'd say AntiSpam was the better choice for most people, though you can easily get a feel for both of them by downloading AntiSpam and the demo of MailScout and trying them out for yourself.
The main drawback of both of these packages when compared to SpamStamp is the need to write filtering rules based on the headers of spam emails while avoiding trapping legitimate email. There are many example rulesets for AntiSpam (read the past messages on the smartgroup for an idea of how many), but you still need to tailor these to your requirements, and update them when new types of spam start to appear. There is also some spam you'll have real trouble stopping if you ever expect to get email from people you don't already know - there's only so much information available in the headers on which to base a decision.
SpamStamp on the other hand bases decisions on the whole of the email, and should gain accuracy with every spam it identifies. It can be taught when it has made mistakes by simply dragging the email from an email client to SpamStamp's iconbar icon - this will cause it to update its statistics and make a better decision next time. It already traps 90% of the spam which gets past AntiSpam on my machine, and that should only only improve as it has more information on which to base its decisions. It is also easy to teach it about new spam patterns with no thought on my part (always a good thing).
The programs which check mail on the server will definitely be very useful on dialup connections - they should reduce download times significantly if you can get the right rule combinations to cut out, say, 80% of spam without downloading it. However, I've found no real drawbacks in installing AntiSpam on a broadband connection either. I set it up to download mail instead of POPstar and while there is a small extra delay compared to no spam checking, it certainly isn't an annoying one. It can be used to get rid of the more blatant spam (things in unreadable character sets, for instance) while leaving SpamStamp to deal with the more subtle stuff.
I'm very happy with the AntiSpam and SpamStamp combination that I've ended up with - it's an arrangement that has reduced my irritation from unwanted email to something close to zero.
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