How Can I Stop Getting Spam? A Tutorial for Webmasters
by Sean Proske
Are you getting too much spam? We all are, but if you're awebmaster the word spam takes on a whole new meaning.
It's not uncommon for the luckiest of email users to receivea dozen or so spam messages each day, while those of us whoaren't so fortunate receive hundreds.
The casual home user tends to be more fortunate, so thisarticle is devoted to those of us with one or more websitebecause webmasters are getting hit by spam ... and hithard.
The reason ... a website doesn't do you much good if youdon't give potential customers a way to contact you, andthat normally means posting an email address on yourwebsite, where it is vulnerable to email address harvestingtools used by spammers. Domain registration records arealso a common source used by spammers.
In order to conduct business online you now need to siftthrough the endless barrage of offers for herbal viagra,pornography, pyramid schemes, and so on.
With such a large volume of spam to contend with, it'slikely you've lost sales due to missing important emailsthat simply floated away in this sea of spam. And there'sno way to really calculate the cost of that lost business.If you've missed email then how can you ever know how muchbusiness you've lost?
If you want to solve the problem, you need to be proactivebecause the sad reality is that if you do nothing, it willonly get worse until finally it reaches the point where youremail account has become totally and completelyunmanageable. Fortunately there are a few options availableto you.
Securing Your Domain Registration Against Spammers
First let's address the whois database, which is a publiclyaccessible database in which your domain registration recordis listed ... and that includes your email address. It'snot uncommon now for people to be spammed at a brand newemail address within hours of registering a new domain.
Go Daddy http://www.godaddy.com is a domain registrar thatnow offers private domain registrations. At the time ofwriting this article, they are the only registrar whocurrently offers this service. Hopefully in time, otherregistrars will pick up on this idea and offer the servicetoo.
With a private domain registration, which costs only a fewdollars more than a regular registration, your contactinformation including your email address will not bepublicly accessible in the whois database.
That's guaranteed to cut down on spam quite significantly asthis very important source of addresses that spammers use,will no longer provide your address to them.
If you don't wish to obtain a private domain registration,then there is another option that will be equally effective.Set up a new email address that you use only for the purposeof providing registration information for your domain name.You can easily scan email sent to that address for messagesfrom your registrar, and delete the rest without having toread it.
Securing Your Website Against Spammers
The other major source, and by far the biggest source ofemail addresses for spammers is of course the mailto linkson your own website. Email address harvesting or extractionsoftware as it's known is cheap, easy to use, and readilyavailable ... and it's very effective. That means thereare a lot of spammers out there with easy access to youremail address.
Chances are hundreds or even thousands of spammers usingsuch software have already harvested your address. And whatcan you do about this? You need to provide a way for yourcustomers to reach you by email, or you'll lose business.There are steps you can take to prevent your email addressfrom being harvested and used by spammers though, whilestill providing legitimate visitors to your site with a wayto email you.
One solution is to make all the mailto links on your sitepoint to a form instead, which will still provide a meansfor people to send you email. Provided you use a CGI scriptthat doesn't require the address to be embedded within theform itself, you can shield your address from email addressextractors.
If you don't want to require people to fill out a form toemail you from your website, then you can get a little morecreative. It is possible to put a mailto link on your sitethat when clicked will still launch the sender's emailprogram, and start a new message with your address in the Tofield ... but without having to embed your email address inthe mailto link where spam software can snatch it. Clickbelow to see an example of how it works.
It looks like a normal URL, and there's clearly no emailaddress anywhere in the link, but when clicked, instead ofloading a web page in your browser as you may have expected,your email program opens up.
How's that possible you might ask? Simple. A little magicwith CGI using Perl or PHP will do the trick. A free copyof a script that does this is bundled with Postmaster Pro,available at http://www.postmasterpro.com which is discussedbelow.
What About Spammers Who Already Have My Address?
So far we've discussed a few fairly simple techniquesdesigned to prevent spammers from obtaining your emailaddress in the first place. But, how do you deal with thespam you're already getting? Your address is already outthere. The solution is to either block or filter.
For either, you'll need software. For blocking, I recommendPostmaster Pro. If you prefer to filter then Spam Assassinis highly recommended. Both run on the server, so there isno need to download spam before filtering it out. That's ahuge time saver if you're not yet on a high-speedconnection. It also makes it a bit less likely you'll endup downloading a virus since email from untrusted senders,i.e. spammers will be significantly reduced.
Spam Blocking Software
Postmaster Pro which is available athttp://www.postmasterpro.com takes a novel approach toblocking spam. It only allows email to be delivered afterpeople who've sent you email have been placed on an approvedsender list. But the interesting thing is that people whosend you email can put themselves on your approved list.This is done simply by clicking a link in an email thatautomatically gets sent to them the first time they sendemail to you, which is perfect for those of us who don'tknow in advance whom we should put on the approved list,i.e. if you're running a business online. It also makesbuilding and maintaining such a list very simple.
Given the fact that spammers normally use invalid returnaddresses, and those who do use valid return addressesseldom read email that's sent there, let alone respond to it(they receive thousands of failed delivery notifications,complaints, remove requests, and autoresponder messagesevery time they do a mailing) ... it's a very effectivetechnique with no chance of blocking legitimate email, as isthe case with filtering.
Spam Filtering Software
For those who would prefer to filter ... Spam Assassin isperhaps the best option. It is available athttp://www.spamassassin.org. Once you have Spam Assassininstalled, it will provide you with very powerful andflexible filtering tools. Spam Assassin is a matureproduct, having been around for quite some time. If you'regoing to filter, Spam Assassin is about as good as it gets.
As with any filter though, you do run the risk of missinglegitimate email from time to time. There really isn't agood way to tell how often this is happening unless you wantto read all the email that gets filtered out, which negatesthe whole point of filtering. If you set your filterspermissively enough though, you should be reasonably safe.For the first month or so after installing any filter, youshould continue to read every single email in order to makesure it isn't set too restrictively to allow legitimateemail through.
By using the techniques mentioned in this article, you cantake back your mailbox, and dramatically reduce, if noteliminate spam.
© 2003 by Sean Proske
Sean Proske is the CEO and founding partner of thewebhostcompany.com which has provided reliable and affordable hosting since 1996.
| DISCLAIMER: The content provided in this article is not warranted or guaranteed by Developer Shed, Inc. The content provided is intended for entertainment and/or educational purposes in order to introduce to the reader key ideas, concepts, and/or product reviews. As such it is incumbent upon the reader to employ real-world tactics for security and implementation of best practices. We are not liable for any negative consequences that may result from implementing any information covered in our articles or tutorials. If this is a hardware review, it is not recommended to open and/or modify your hardware. |
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