Testing and optimizing subject lines in an effort to find that perfect teaser to increase opens will forever be a challenge. Significant digital ink has been expended in choosing sides for the clever vs. straightforward debate. Those coming down on the clever side have begun using symbols in email subject lines in an effort to boost opens. Marketers have gone “all-in” with this new strategy over the last few months, in particular. But is it really working?

In short, yes it is. But there’ s a little more to the story.

But what is a symbol anyway? Fonts are technically created entirely from “symbols,” but those aren’t the symbols I’m referring to. I’m talking about the hundreds of different symbols derived from Unicode that are usable in subject lines, which are different than images. These Unicode symbols are widely used to replace words or simply add flair to the subject line. Currently, the most commonly used symbol is the ♥ (heart). But many of the more creative-forward brands have experimented with this new art form by combining several symbols into one coherent illustration. For instance, a recent Jeep email used 9 individual symbols to create this – ☀|||||||☀ – representing the iconic appearance of the Jeep’s headlights and 7-slatted grill.

Creativity is always a draw and you can have some fun creating symbol-heavy subject lines, but this one simple question should drive your decision making: Is performance affected? What we’ve found here at DEG is that inserting symbols into subject lines hasn’t shown any drops in deliverability rates and, more importantly, the open rates have seen drastic increases. Emails with symbols have been reported to increase open rates anywhere from 10 to 50 percent.

Here are a couple of examples:


 Date SentSubject LineAvg Open Rate (for 2012)Campaign Open Rate% increase in Open Rate  (campaign-avg/avg)
Brand A
09 November 2012★ Free Delivery + 24 Month Financing ★9.1%12.3%34.8%
05 December 2012⓬ Buys of Christmas12.2%33.7%
20 December 2012❄ Stuck At Home? Shop Online, Pick Up Later9.9%8.6%
Brand B
12 December 201212-12-12 – ⓬ hours only! – Save 12%12.6%17.9%42.7%


In these examples, it’s easy to see that the use of symbols has an impact for these brands and with these particular subscriber segments. But will it work for you? The best advice I can give is to find out. Run a test on your own to see what works for your brand. In a technical sense, some symbols will work and some won’t. Be sure to test on mobile devices, as well. Mobile opens are constantly increasing, which makes testing on mobile vital – especially since each device handles Unicode symbols differently.

The downside to symbols is in fact that not all symbols render in every ISP and on every mobile device. For example, in iOS some symbols will simply render as an empty rectangular text box, others will render as expected, and still others will actually be converted to emoji icons (of course rendering as emoji is a good thing since it’s an upgrade for user-experience). Finally, Lotus Notes and Outlook 2003 are still in use, and neither will render symbols at all. So more research will need to be conducted to determine long-term effects and subscriber fatigue, but just like anything else, there’s never going to be a silver bullet.

Of course standard guidelines for subject lines should still be considered, but symbols have definitely proven successful to dramatically increase opens. This means email marketers have that much more to test, but if executed well, the rewards will be plentiful. As with every other element of your email send, the number one consideration in using symbols is to ensure that the content is relevant to the subscriber. Just because everyone else is using symbols doesn’t mean that it’s right for you.

Good luck and test, test, test!

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