Preventing Spam: Bulletproof Solutions

• By Vitaly Friedman
• December 14th, 2006
• ASCII, Domains, Email
• 26 Comments

Spam is probably one of the most difficult problems we have to deal with. E-Mail-filters, such as those used in GMail, provide accurate results, but not every company is willing to use extern services for its private mails. The problem occurs when web-developers have to display e-mail-addresses on a web-page.

How can you make sure that not a single spam mail will find its path to the inbox of your client? Or, speaking in more concrete terms, the question is, how should you display e-mails on a web-page in order to minimize spam attacks? Let’s take a look at some modern and bulletproof solutions and techniques which will help you to prevent spam in your mailbox or the mailbox used by your clients.
Links checked: May/30 2008.

Avoid stereotypes

Sometimes web-developers tend to rewrite the original e-mail, so spam-bots can’t recognize it. This method might solve the problem, but spam-bots might catch on this sooner or later. Besides, many users might have problems decoding it – unless you provide some instructions how to decode the text. Most popular approaches are:

• Replace dots with “d-o-t”, “@” with [at] and as many spaces as possible.
  Example: e-mail@office.com -> e-mail [at] office [d-o-t] com
• Insert some characters before and after the “@”-symbol.
  Example: e-mail@office.com -> e-mail {!@!} office.com.
• Avoid stereotypes – e-mails like info@domain.com, service@domain.com, admin@domain.com are likely to be spammed anyway.

Replace text with images

Apparently, most spam-bots don’t scan images on the web (yet?), so it seems reasonable to place the text inside of an image without referring to it as an e-mail-address. There are free web-tools which generate images “on the fly”, so the only thing you have to do is to place them on web-pages.

• E-Mail Icon Generator for GMail, Hotmail, MSN, Yahoo!, AOL and many more.
• Signature Generator does basically the same as E-Mail-Icon Generator.
• Mask Email Image Generator will create a JPG image of your email address. Use it in place of text to fool those evil spiders that seek out email addresses for purposes of sending junk email.
• Safe Mail creates your own email image in three steps.

Replace text with ASCII and Javascript-coded text

Another popular approach is to represent e-mail-adresses as ASCII code or Javascript-coded text. Users don’t see any difference in e-mail-presentation, but spam-bots won’t find the e-mail analyzing the source code – well, not yet. Some web-tools to convert e-mail links to ASCII code:

• Online Email Protector: to use, simply type you email address below and then click in either of the textboxes. You can use the simple link code, or the more complicated Javascript link.
• Spam-me-not E-mail Link Obfuscator: you can choose between different encoding modes: decimal notation will encode every character in decimal ascii code, hexadecimal notation will encode every character in hexadecimal notation, random-mixed notation mixes encoding characters randomly, this is the default and recommended choice.
• Email Riddler is an online tool that encrypts and transform your email address into a series of numbers when displaying it, making it virtually impossible for spam harvesters to crawl and add your email to their list.
• Advanced Email Link Generator with Anti-Spam Encoder: this tool will generate mailto: links you can copy and paste into your web pages and emails. The Anti-Spam Encoder is an encoding scheme designed to cloak email addresses from spammer’s email harvesting robots, yet be visible and readable for your site visitors.

Bulletproof Solution

A simple solution I’ve been using for my recent project turned out to be the most effective I ever had. The most important rule to avoid spam is never mention it somewhere in the Web. So what I’ve suggested to do is to create two e-mail-accounts – the one for business contacts, which will be used only for communication with partners and serious clients and the second one, which will be decoded and published on the Web for any other purposes.

Once a potential client has written at the e-mail-address mentioned on the Web, the company will continue its communication via the first, “business” e-mail. On the other hand, brief questions or some small remarks will be responded via “open” e-mail, published online. Once the “open” e-mail gets included in spam databases and the company starts to get junk mail, it will be replaced by a new one.

This way your primarily, business contacts will always stay in touch with you via your business account and you reduce the amount of received spam to 0%.

Using GMail spam-filters externally

Another useful technique to minimize the amount of spam-mails ending up in your inbox is letting it through gmail-filters. Unfortunately, GMail doesn’t have a function which would enable users to use Google’s filter directly. However, you can forward all the mails coming to your e-mail-box to your GMail account, and set your GMail account to forward the filtered messages to your private “clean” e-mail-account. The results aren’t always accurate, but you’ll see the difference immediately.

Further articles

• 99 Email Secuity and Productivity Tips: the 99 tips in this article make up the best in email practices. From how to ethically use the ‘BCC:’ to what attachments will make your mobile emailing compatible with everyone else’s, this list covers everything you need to know about emailing.