There's a certain hyper-sensitivity surrounding e-mail these days, what with new federal legislation and an increased suspicion about e-mail's effectiveness as a marketing vehicle. One interesting offshoot of this uneasiness is a growing trend for companies to employ spam filters, or more precisely, the software that includes such filters, as a testing tool for their e-mail campaigns. The thought, reasonably enough, is that by running campaigns through these filters ahead of time, and adjusting the copy accordingly, those campaigns will be filtered less, successfully reach more inboxes, and ultimately generate a higher response.

We also use such tools (notably Lyris Mailshield, see: http://www.mailshield.com/), and they've become a handy method of "scoring" e-mails as a way to gauge to what extent their content will be flagged by common filters. However, we do so cautiously, and preach this same caution to our clients. The danger, we feel, is that, used too religiously, spam filtering software can become the ultimate arbiter of what language makes it into an e-mail campaign, sometimes at odds with what we know is otherwise effective direct marketing copy.

Two recent campaigns for technology clients bear this out:

The first example was a campaign targeting customers of a leading business intelligence solution. We tested two subject lines, one more benefit-oriented ("Acmesoft 3.0 - Upgrade Made Simple") and the second promoting the offer ("Acmesoft 3.0 - Free Upgrade Guide"). The results were startling: the offer-oriented subject line generated almost twice the response as its competitor (13 percent compared to 7 percent), even though it included the word "free".

The second example was a lead generation campaign for a large enterprise software company. In this case, part of the test was to measure an HTML version of the message against a plain text version. The HTML version outperformed its plainer counterpart by more than 60 percent.

It's highly likely that, as filtering software becomes more and more effective, these same tests run a year from now, maybe even six months from now, may yield different results. In the meantime, however, we conclude that it's premature to push aside proven direct marketing techniques simply because your e-mail software tells you otherwise.