How to Use Symbols in Email Subject Lines

Dutch HollisIn my last post, I promised a discussion of the use of symbols in the subject lines of your emails. Today, we’ll discuss how the use of non-alphanumeric symbols (like ♥, ★ or☺) can help your message stand out in a crowded inbox. Standing out is the first step in getting the treasured open and while a trick like this works, it can’t be used all the time. Shouting in a crowd will get attention too, but not if everyone else is shouting, or if you’re always shouting.

First, let’s just get it out of the way that it works (at least for now). Clearly, subject lines like this work only if the emails get there. Several web publications and industry blogs have raised the concern that the use of symbols in subject lines heightens the risk of an email being blocked as “spam.” Our test of that theory, using identical creative with different subject lines – one with an icon, and one without – showed that both versions generated very similar rankings on major spam filters, making them equally compliant regardless of the use of symbols. Delivery rates have proved out the pre-flight testing.

Better yet, our tests have shown that the use of icons in subject lines resulted in higher open rates. We recently ran an A/B test with an audience of about 110,000. Half received the email with a symbol in the subject line while the other half received the identical email creative with a subject line that did not contain a symbol. The open rate for the subject line with the symbol was 6.34%, while the open rate for the subject line without the symbol was 5.66%, representing a statistically significant lift for the subject line that included a symbol.

So when might you want to use symbols in your subject line?

Perhaps to make a point:

Or for branding:

To invoke an emotion:

…Or the feeling of a season:

Note that the last example is from an iPhone and the symbols are interpreted with color and depth as discussed earlier.

So use them, but be careful. Overuse of symbols in your subject lines will dilute their effectiveness over time. Like the good silver, bring out the icons when you’re looking for extra attention from your customers. As with so many things in life, a little goes a long way. And be sure to run your own tests to ensure that the symbols you use are adding value rather than clutter.

Here are some tips for the best use of icons in your subject lines:

  • Use symbols that provide thematic support to the subject line and message itself
  • Use symbols in the forefront of the subject line for best impact
  • Use simple symbols that remain legible on a small scale
  • Test how the symbols render across different email clients, web mail sites and mobile devices
  • Test using different symbols, and monitor open rates as it relates to the “newness”
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