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Tune Up Your E-Mail Program With SpamAssassin

  |  December 7, 2005   |  Comments

A step-by-step guide to seeing your e-mail the way this spam filter does.

Guess what this ClickZ column scored when we ran it through SpamAssassin? The popular open-source email filter program penalized it 2.543 points; not enough to get it blocked by most mail servers, but higher than normal.

That’s because this column talks about the spam indicators SpamAssassin is trained to detect. (Too bad SpamAssassin can’t tell the difference between real and demonstration spam.)

In part one of our SpamAssassin primer, we outlined the program’s basic features and how it can affect deliverability. This time, we’ll demonstrate how SpamAssassin works on real copy and how to use it to fine-tune your own email program, both to improve content and increase deliverability.

Example One: We Flunk a Test

Offending material: "The Utah Registry has been challenged in court by an adult entertainment trade group...."

This real-world excerpt came from The Intevation Report, our corporate newsletter. We opted to leave the content as it was because the message was otherwise clean. The details:

  • SpamAssassin test flunked: "Something for Adults," refers to possible pornography

  • Point value: 1.5

  • How to fix it: Break up the close association between "adult" and "entertainment" by rewriting as "adult-oriented."

Whatever you do, don’t try to fool the filters by misspelling words or replacing letters with characters. It’s a classic spammer trick that filters are trained to catch, and it looks unprofessional.

Example Two: A Deliberately Bad E-Mail Message

Offending material: We created an HTML message for a fictional skateboard retailer and loaded it with potential test-flunking elements, such as malformed HTML code, spammy-sounding content, and a high-image/low-content ratio.

Here’s a screenshot of the email message:

Click on thumbnail to view full size screenshot

The details:

  • SpamAssassin tests flunked:

    • The HTML font color is similar to the background.

    • The message claims the recipient registered with a partner.

    • The subject line is in all capitals.

    • The sender line ends in numbers.

    • The unsubscribe page URL includes "remove" (two instances).

    • The message includes phrase, "See for yourself."

    • It includes phrase. "risk-free."

    • The HTML contains text after the body close tag.

    • There’s an HTML tag for a big font size.

    • The HTML contains text after HTML close tag.

    • The subject line starts with "free."

    • There’s HTML included in the message.

  • Point value: 9.38.

  • How to fix it: First, we corrected the HTML coding errors. Then, we rewrote the body copy. See the corrected result here:

Click on thumbnail to view full size screenshot

Three SpamAssassin Strategies

We previously recommended running your email marketing message through a content checker, whether a free or promotional service, third-party solution, or proprietary application provided in your email service provider’s solution or in-house software, to spot and correct problems before you hit "send."

These three strategies help you use the SpamAssassin tests to tune up your email program the right way:

  • See your email as SpamAssassin does. SpamAssassin breaks messages down into components instead of viewing it as all one piece: headers, subject and sender lines, body content, HTML code, pings on blacklists and whitelists, and so forth. You should adopt this manner of viewing email and work to correct problems in each component, not just the components that affect you most, such as subject line or body content.

  • Test your templates. Your primary newsletter or promotional message may not be the only email that gets tangled up in filters. Take all your email templates: company newsletter, sales promotion, order or subscription confirmation, welcome message, complaint response, announcement, and so forth, and run them through the content checker with no body copy or coding beyond what the template requires. This solves two problems:

    • You can correct any problems in recurring code, content, and reputation areas that don’t get the same attention as your fresh copy. These include blacklisting, poorly constructed HTML code, and offending language in your footer area.

    • After this, you’ll run mostly fresh copy through the content checker. You can do this while you’re still in the production process instead of waiting for a complete message to be formatted. (This approach won’t help if you get added to a blacklist later, which is why you need to check your blacklist status periodically; see below.)

  • Use the checker with caution. Checkers provided as a free or promotional service on a company Web site may not be using the latest SpamAssassin version (3.1.0 in 2005), not configured to include the same tests an ISP corporate or individual mail server might use, or not assess the same point penalties. As a network administrator and ClickZ reader told us, he filters email simply if it includes what he perceives as aggressive, spammy words such as "free."

Bottom line: A zero or low score is reassuring, but it’s just a start. Review the content one more time. Check the IP address used to send your message against a blacklist clearinghouse like DNSstuff.com. Monitor your reply mailbox for any filter or block reports.

And as always, keep on deliverin’.

Want more email marketing information? ClickZ E-Mail Reference is an archive of all our email columns, organized by topic.


Kirill Popov and Loren McDonald

As director of ISP relations and delivery, Kirill Popov creates and enforces strict usage and anti-spam policies, maintains ISP and community relations, and oversees all abuse and policy investigations and inquiries for EmailLabs clients. Kirill works with clients on best practices, content, design, and list hygiene to minimize potential delivery issues. He's a registered member of the SpamCon foundation and representsEmailLabs on AIM's Council for Responsible E-Mail.

Loren McDonald is vice president of marketing at e-mail marketing automation company EmailLabs, overseeing corporate marketing activities and client consulting services. He has 20 years experience in marketing, consulting and strategic planning. Earlier, Loren was founder and president of Intevation, an e-marketing services firm specializing in e-mail and SEM. He's held executive marketing positions at companies including USWeb/CKS (marchFIRST), NetStruxr, and Arthur Andersen.

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