A little too proactive? Perhaps, but it’s happening with email right now. To combat the problem of spam – about half of all email at the moment – Internet service providers are installing and using “spam filters” to preemptively trash the mail that looks as if you didn’t ask for it. It’s a technology that customers have been waiting for – but it worries the honest marketers who are on the sending side.

Fighting back

You may be familiar with the personal junk mail filters within your own email program, such as Outlook. Using them may give you a warm feeling, but it does absolutely no good. Spammers are always changing return addresses and subject lines, so your personal spam rules, like old generals, are always fighting the last war.

Enter industrial-strength spam filtering. Although large corporations have for years had spam filters to protect their knowledge workers from time- and bandwidth-wasting emails, in 2002 this technology finally broke into the consumer mainstream. ISPs have begun to install professionally built filters on their email servers to catch the spam upstream before it gets to you.

This has two advantages: people don’t have to maintain personal spam rules, and ISPs get credit for fixing the problem.

But the sword cuts both ways. As sophisticated as these filters are – and they have to be to compete with the spammers – they occasionally will trap legitimate email and mark it as spam. If you sent your friend an email saying that you had just successfully refinanced your mortgage and had your septic system cleaned…well, it may not get through. This “false positive” problem is of paramount concern for mass mailers, and also of growing concern for B2B marketers.

False positives reduce everyone’s return on email marketing, and can seriously compromise relations with customers if invoices and product updates get hung up in the spam filters. Learning how to elude the filters is another trick that marketers have to learn.

How to keep your email out of the spam filters

Our first set of rules is good practice anyhow. Pay attention to the basics of email marketing. Keep your house list one hundred percent opt-in, have high standards for ongoing “list hygiene,” purchase only verifiably opt-in mailing lists and work with credible email vendors.

Although these good practices don’t have an immediate affect on the how individual emails are received by the filters, they help keep you far away from the dreaded email “blacklists” of untrustworthy senders.

Blacklists

If someone has been identified as a spammer, his or her IP address can be added to a “blacklist” that serves as another filter that ISPs use. Nice concept, but there are some holes. The occasional crude application of these rules means that your IP address (or all of those belonging to your own ISP) might unfairly appear on a blacklist. Compounding the problem is the fact that there are hundreds of blacklists in use. Legitimate email vendors wind up on these lists too.

Blacklists complicate your efforts to diagnose your “false positive” problem. If you send out a test email and your AOL account doesn’t get it, it could be due to the content of your email or it may be that your company or ISP has wound up on a blacklist. Complicating the situation even further is the fact that ISPs use different content filters and blacklists.

Even though monitoring your “test accounts” is an imperfect method of finding out if you’re on a blacklist, it’s cheap and fast. If you’ve got a lot riding on your email campaign, and are having trouble getting your emails through, consider going to an email vendor. Many offer a service that will query for your appearance on the blacklists.

Word choice

Watch your language. Although spam filters consider many things when examining emails, the actual  words appearing in the subject line and the body of the email are most important. Happily, you have the most control here as well. Avoid words such as “free,” “click” and hyperbole such as “guaranteed,”

which are trigger words for the spam filters. There are scores of others to avoid.

Shun words in all capitals, punctuation such as $ and !, and avoid including anything but the briefest unsubscribe instructions.

Trigger words

No single word will doom an email (although I’d rather not stake my livelihood on selling Viagra through the Internet). Most spam filters add up incidences of suspicious language and other factors, and mark an email as spam if it is over a certain limit.

SpamAssassin is one of the more popular filters. Click here for its long list of tests. You’ll find trigger copy and a number of other intriguing entries (the “Dear” salutation if you can believe it).

Content checkers

Email vendors are offering free content checkers. Enter your email into a form on their site before sending your email, and they run it past their own filters as a sort of test. Naturally, they’d like to speak with you about your needs. Assurance Systems has a form test here. It also has an informative white paper about spam filters.

Email managers at large businesses should look outside their own department for spam filter candidates. Sales letter templates and standard customer service responses should get reviewed for language. Your own web pages ought to get a quick once-over, since they are occasionally sent through email.

Any copywriter who writes online copy ought to spend an hour reviewing the language triggers. Experienced copywriters are unlikely candidates to pen something awful such as “limited-time offer,” but they ought to know about some of the minor triggers. Avoiding an accrual of these minor red flags in a single piece is essential.

Other tactics

Test accounts

Get an AOL account and several different free email accounts for testing. Send your email to yourself before you mail it to customers – and make sure it gets through.

Split the list

Then, when you’re finally ready, consider splitting your mailing list into several parts. This makes your email blast look less suspicious to the filters, and has the added benefit of allowing you to measure the effectiveness of differently worded messages.

Read on

Anyone concerned with spam filters ought to sign up for the EmailSherpa newsletter. The whole family of MarketingSherpa emails is well regarded.

Debbie Weil, a journalist and copywriting consultant, has a useful review of writing for spam filters here.

And for the rawest, unfiltered, unvarnished repository of knowledge, visit your local newsgroup, news.admin.net-abuse.email in this case, where elite spam hunters mingle with the novices and the trolls. You’ll read some fairly knowledgeable man-on-the-street coverage of new issues, and often find the answers to obscure questions.

For most people, spam filtering is a great thing. Your in box is cleaner and you can concentrate on revenue-generating email. When sending email, sticking to a manageable set of guidelines means your email will probably not run afoul of the filters. After all, you wouldn’t want to trust your catalog to the postman.

Andrew Benkard is president of Benkard Campaigns, a contract consulting firm that creates interactive marketing campaigns. For a complimentary consultation to see how your marketing efforts could be better stitched together, visit  http://www.benkard.com or call Andrew at 1-609-936-7230.