In the opening of this post, I said I had no magic words for you. Well, maybe I do. Only two, though: "Free Shipping." According to Adestra's 2013 Email Subject Line Analytics Report (see), using the words "Free Shipping" in an email subject line will increase email open rates. 50.7%. “Free shipping” will also increase click-through rates by 135.4%. These metrics are for the overall sample of emails measured by Adestra – a pool of over 2.2 billion emails. Just to give you a little taste of some of the data from this study, here's the chart of top and bottom performing words for email subject lines from Adestra's general sample. Be sure to choose your keywords carefully as some can trigger SPAM content filters. Here is our list of spam words to avoid. What words work best in email subject lines? This is an interesting table to ponder. But just for a bit of contrast, and for proof that you shouldn't take what marketing studies say as gospel, here are the results of a very interesting test conducted by Marketing Experiments.
Their test cells specifically used the words "free" and "home delivery" in the subject lines. But in the Marketing Experiments test, the email subject line "Home delivery" didn't win. An email subject line a/b split test from marketing experiences 3) [Brackets] Image Masking Service Some marketers use parentheses in their email subject lines, just like the Marketing Experiments example. Parentheses can highlight a word, phrase, or brand name in a way that makes a difference. Writer Joanna Wiebe was skeptical about the effect the brackets would have on her subject lines…until she tested them in two parts. For her test, she included her company name in parentheses. His tests show that it actually helps increase response.
Joanna Wiebe's Subject Line Tests Here's another test run by Wiebe where the parentheses again don't beat any parentheses: More tests on Joanna's email subject line There's plenty of other anecdotal evidence that marketers get a boost with brackets in subject lines. Sometimes emails contain a call to action in parentheses. Other times it's the company name, like in this example. You probably won't see a massive 30% boost if you add hooks to your emails, but it's definitely worth some testing. 4) Subject line length: keep it short! Email subject line length is tested and discussed more than anything else. Almost all tests favor shorter subject lines.