Apparently It’s Now Safe (Again) to Use “Free” in a Subject Line

In follow-up to the recent 2013 Marketo Summit, the marketing team at ReachForce, a leading provider of B2B data services, sent a message to attendees (including this blogger) crowing about the success of their traffic builder campaign, an email that generated a 42.8% open rate and resulted in ReachForce hosting the most heavily visited booth during the event. The subject line that generated such success?

using free in subject lines“Marketo Summit – Free Beer, Gold for Everyone!”

There are all sorts of conclusions one might draw from these results – most notably, when and how to use humor in business campaigns – but here’s the factor that struck me most: the word “Free”.

No-one uses “free” in subject lines any more, do they? Well, apparently, they do. And though it’s only one data point, I found it somewhat revelatory that the ReachForce campaign generated an open rate well above industry standards, even using a term that by all accounts is supposed to guarantee your campaign ends up being caught in spam filters.

Other experts have seen similar results. In his post “7 Email Subject Line Myths Exploded,” email consultant Tim Watson writes that spam trigger words like “free” aren’t the problem they once were, because whereas in years past email was largely filtered on content, now the biggest variable is reputation. In other words, Watson contends, content will only cause you problems if you’ve received spam complaints in the past (or worse yet, have been blacklisted) and your email reputation is weak as a result.

In a related post, inbound marketing software provider Hubspot reported on an A/B test using the word “Free” and concluded that the difference, at least in terms of deliverability, was statistically insignificant. However, Hubspot also noted that click-through rates increased when the word “free” was excluded. It’s worth pointing out that Hubspot’s test was less than ideal because, in the second subject line, they substituted the word “free” with the word “SEO.” A cleaner test would have been to simply exclude the term altogether, for example:

[Free Guide] How to Master Internal Link Building for SEO
[Guide] How to Master Internal Link Building for SEO

since, by using [SEO Guide] as their test, Hubspot introduced another variable – namely, the word “SEO”.

But, again, anecdotally this also suggests that, at the very least, “free” has nowhere near the killing effect that B2B marketers of recent vintage have been trained to believe.

So, what to do? Well, test, of course. At our agency, we’ll be weaving tests of the word “free” into multiple client campaigns over the coming weeks and months. If the findings are significant, I’ll report back here in the comments. In the meantime, if you’ve run similar tests of late, please share your observations.

A further aside – if it’s indeed true that “free” isn’t the spam trigger it once was, this also proves that no email marketing best practice is true forever. Way back in 2007, I wrote a post (“The Myth of Why You Shouldn’t Use “Free” in Subject Lines”) on this same topic, and reported that a recent test (back then) showed the term had increased open rates by 45%. In subsequent years, however, similar tests showed “free” to have a consistently negative effect. Now, apparently, the pendulum has swung again.

4 thoughts on “Apparently It’s Now Safe (Again) to Use “Free” in a Subject Line

  1. Maria Pergolino

    At Marketo we struggled with this and similar words tied to the Gift Card for Demo offer. I think we ended up with something ridiculous like 30 tests before we came up with our final version. That said, one of the biggest (and fastest) ways to narrow this down was not just with testing out to our subscribers, but to use deliverability and rendering tools like Return Path and IBM (Unica’s Pivotal Veracity). These can help you figure out if your email is being delivered even before it is sent. If you are using Marketing Automation these tools can be integrated into your process.

  2. Howard Sewell Post author

    Great tip, Maria – thank you. Of course, deliverability isn’t the ultimate metric, correct? We’ve had many examples of client campaigns in the past where one test cell generated lower deliverability and open rates, yet that same cell resulted in more leads. Historically, “free” is one of those conundrums … it can trigger spam filters and result in fewer emails being delivered, yet for those who DO receive the email, it can drive higher engagement. (There’s a reason David Ogilvy called “free” one of the “two most powerful words in advertising.”)

  3. Maria Pergolino

    I think that if you are emailing well you are only sending offers (especially things you are doing free) to a target, relevant group. Because of this everyone is important, especially if you are trying to weave a story (instead of just blasting out information). Because of this you should:

    -Create a plan for the email including highlighting what is going to drive conversion (scarcity, limited time, exclusivity, etc.)

    -Draft an email that meets the plans expectations

    -(if at all possible) Test the email with a tool like Pivotal Veracity to see 1. is it making it into the test email boxes 2. what words are they highlighting may have issue 3. is it rendering properly (If this is not possible at least do some rendering testing with a site like

    -Send to a test group, looking for issues with deliverability (bounces), opens (deliverability or subject line problems), click throughs (offer strength, offer relevance, content’s alignment with email subject) – potentially doing AB testing during this test send.

    -Adjust based on test group results

    -Then send to the target audience

    Wow, I could go on about email marketing for way too long.

    You rock Howard!

  4. Matt Heinz

    Deliverability aside, depending on what you’re offering and who you’re offering it to, I wonder if “free” cheapens the offer. It may be free, but are there other ways to communicate that? Plus, coupling a variation of “free” with an urgency driver (limited time, limited supply) can accelerate response rates as well.


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