Editor’s Note: The MarketingExperiments community is an interactive group with a great deal of questions and answers between marketers and their peers as well as with the MarketingExperiments staff. Occasionally we publish these interactions on the blog when we think there is a particularly good question that our readers can benefit from…
QUESTION:
I recently watched The Five Best Ways to Optimise Email Response seminar by Dr Flint McGlaughlin. I found it extremely enlightening and it provided a lot of food for thought. However, I have a quick question with regards to slide no. 22.
I appreciate your time and I’m sure you receive plenty of mailings of this nature; therefore I will get straight to the point.
In this slide, the recommendation is to change the subject line of the mailing from “Thank You For Making Us Your Florist Of Choice” to “15% Off – Our Way Of Saying Thank You!”
I understand why the wording would be changed to make it more endearing to the receiver but I wondered if the symbols added would increase the risk of the mailing being filtered and more inclined to be highlighted as spam – therefore reducing the success of the mailing. 
In my experience I steer clear of any symbols in the subject line when sending large mail shots, especially %, ! and £. Am I being too cautious?
Kind regards,
Chris, BA(hons) Business & Marketing
Marketing
London
ANSWER:
Hi, Chris. Thanks for your question.
If I might broaden the question slightly to interpret its essence as a transferrable principle, could I restate it as…
How much validity is there to the conventional wisdom that, in the Subject Line of an offer email message, numbers, certain symbols (especially £/€/$, %, and !) and “SPAM words” such as “Free” and “discount” will cause a dramatic reduction in deliverability, and consequently effectiveness?
… if so, then it’s surely an important one.
In the case of the particular company and study referred to on Slide 22 – that was precisely one of the questions we set out to answer.
What you couldn’t see in the context of Dr. McGlaughlin’s presentation at the MarketingSherpa Email Summit in Miami is that this particular two-treatment comparative vignette was just a tiny part of a much larger and broader study. We intended to test the specific, widely accepted presumption you mentioned.
We were also exploring a host of other best practices to see how valid they remained through the evolution of regulations as well technical filter changes by email service providers (ESPs) since the time they were first introduced and anecdotally adopted (around 2003-2005).
This was important because we know from our foundational Offer/Response-Optimization principles of “clarity trumps persuasion” and “specificity converts,” that the clearer and more specific subject line – i.e., the one with the “15% Off…” copy – should convert better.
What we found was that there was, in fact, a small but significant difference in deliverability – interestingly, it was more pronounced among the smaller ESPs. In addition, as we had predicted based on the “eme” heuristic, the Open Rate actually declined (…by more than 25%).
In the end, though, the central research question was “Which email subject line will result in the greatest projected net revenue?” As revealed in Dr. McGlaughlin’s presentation, despite the slight dip in Delivery Rate, and the (what would otherwise have been alarming) drop in Open Rate, the Click-through Rate (CTR) to the landing page was 60.3% higher.
What he may not have mentioned is that, in direct answer to the research question, the Treatment subject line yielded a 56% increase in projected net revenue vs. the Control.
So, while it appears there is still at least some validity to the commonly held belief that special characters in the email Subject Line reduces deliverability, our research (this experiment plus two others conducted with different products and industries) suggests that when they serve to do so, these negative factors are dwarfed by the power of clarity.
I hope that’s helpful, Chris.
All the best,
Bob Kemper
Director of Sciences
MECLABS Group, LLC
Dr. McGlaughlin will next be teaching and speaking about email marketing at MarketingSherpa Email Marketing Germany 2010 in Munich on March 8th and 9th.
Dr. McGlaughlin’s four-hour workshop and keynote presentation will cover email capture rate and quality, open rates, conversion, and building customer trust and loyalty with email. He will also be conducting live optimization of audience submissions – a lively and always-popular segment.