9.4 Avoiding Spam and Junk Email

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9.4 Avoiding Spam and Junk Email

Unwanted electronic mail is the number one consumer complaint on the Internet today. A 1999 study by BrightMail, a company that develops antispam technology, found that 84 percent of Internet users had received spam; 42 percent loathed the time it takes to handle spam; 30 percent found it to be a "significant invasion of privacy;" 15 percent found it offensive; and ISPs suffered account churn rates as high as 7.2 percent as a direct result of spam.

9.4.1 Protect Your Email Address

To send you junk mail, a spammer must have your email address. By understanding how spammers get email addresses, you can keep your mailbox relatively spam-free:

Don't put your email address on your home page

One place that spammers get their email addresses is from web crawlers that search the Internet for email addresses. These email addresses are then sorted, indexed, compiled onto CD-ROMs, and sold. The easiest way you can keep your email address from being put into these collections is to avoid putting your email address on a web page.

Take your name out of online directories

Another source of email addresses that spammers use are online directories operated by organizations like AOL, BigFoot, and Yahoo. Although these organizations all try to fight spammers and prohibit spammers from using their directories to collect email addresses, invariably online directories are used for precisely this purpose. You can avoid a lot of spam by simply asking that your email address be unlisted.

Don't post to public mailing lists

If you post messages to public mailing lists, there is a good chance that spammers will scrape the messages posted to these lists for valid email addresses. The archives of mailing lists are also a rich source of fodder for spammers. You can avoid having your email address captured by spammers by not posting to public forums, or by posting only from email addresses that you do not value.

Don't post to Usenet

Likewise, Netnews postings on Usenet are another source of email addresses for spammers. If you post to Usenet, you should expect to get spam sent to your return address.

Pick an unusual username

Even if you never post your email address in a public place, if you have a popular username like bob, kathy, or even bob7, you should expect to receive some spam. Spammers frequently engage in dictionary attacks that is, they have a dictionary of likely usernames, and they send their spam messages to every single one of those usernames at the top 1000 Internet service providers.

9.4.2 Use Address Munging

If you don't want to become an electronic hermit, you might consider using a technique called address munging or address mangling. This technique involves making obvious modifications to your email address so that the web crawlers operated by spammers will not be able to harvest your actual email address. For example:

Instead of using this email address	Use this munged address
[e-mail]	[e-mail]
[e-mail]	[e-mail]
[e-mail]	[e-mail]
[e-mail]	[e-mail]

In general, it is considered better form to mangle the domain name. If you mangle the username (e.g., "[e-mail]," rather than "[e-mail]"), the spammer will still deliver your email message to your ISP, and then your ISP will need to figure out what to do with it.

When you mangle the domain name, the spammer is unable to deliver the spam message to your ISP.

9.4.3 Use an Antispam Service or Software

Yet another alternative in the war against spam is to employ an antispam service or antispam software.

Antispam services are organizations that analyze your incoming email and determine whether or not it is spam. Some services attempt to match the incoming email against known spam. Other services keep track of a whitelist of addresses from which you are willing to accept email; other people who attempt to send you a message get a note back asking them to click on a link or reply to an email message to be added to your whitelist. The theory here is that spammers, who mostly use bogus return-addresses, won't ever see the email messages with instructions on how to get added to your whitelist.

Two popular antispam services are:

• BrightMail personal edition (http://www.brightmail.com/ )

• SpamCop (http://www.spamcop.net/)

Antispam software is software that performs much the same function as the antispam services, except that the software runs on your mail server or on your desktop computer. The big advantage of these programs over antispam services is that your mail never leaves your computer. The disadvantage is that you need to maintain the software.

Two popular antispam programs are:

• SpammerSlammer (http://www.nowtools.com/)

• Spam Exterminator (http://www.unisyn.com/)

A great deal of useful information about stopping spammers, and links to antispam services, may be found at http://www.junkbusters.com/. This site also has information on stopping junk paper mail, web banner ads, as well as those annoying telemarketing calls.

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