The Myth Of Why You Shouldn’t Use “Free” In Subject Lines

I continue to read opinion pieces in industry publications and e-newsletters imploring marketers not to use “Free” in e-mail subject lines, based on the argument that “Free” will trigger spam filters and result in e-mails being dumped into junk mail folders.

To which I say: bunk.

Yes, it’s true that “free” will trigger spam filters. No, it’s not true that this automatically makes the word a bad idea. Decades ago, marketing guru David Ogilvy called “New” and “Free” the two most powerful words in advertising. Little has changed since. Fact is, “Free” will reduce the deliverability of your e-mails, but in our experience, it also increases response rates. Why? Because “Free” still resonates, still grabs the reader’s attention, whether in an advertising headline (as in Ogilvy’s day) or an e-mail subject line.

Case in point – we recently tested 4 subject lines for a software client, 2 of which included “Free”, 2 of which didn’t. The 2 subject lines that included “Free” generated the highest open rates (the metric most impacted by subject line). Most telling, in a direct test between 2 subject lines with the same message – one that included “Free”, one that didn’t – the “Free” version generated an open rate 45% higher than the alternative.

Bottom line: don’t let spam scores and filters rule your e-mail creative. Particularly if you’re e-mailing to in-house list (where the cost to test is nominal at most), always test a version of your subject line using the word “Free”.


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