Do You Want $150 for FREE? Measuring the effect of language on marketing email open rates

Marketers have made analyses of which words are conducive to successful marketing emails. We propose taking a deeper look into the language to discover which kinds of words and linguistic features cause more emails to be opened. This article compares the linguistic structure of 31,812 email marketing subject lines with the opening rate of each line. Each subject line was tagged for parts of speech, personalization features, punctuation and whether they include “power words”. Some linguistic features, such as exclamation points and nonstandard ways of writing, have a statistically significant effect on increasing open rates, but notably the use of ALL CAPS does not. On the other hand, some features are shown to have a negative effect on open rates. We suggest several reasons for the positive and negative correlations. First, email software limits the ways in which marketers can emphasize subject lines. Second, readers' familiarity with email and the practices of computer-mediated communication most likely play a role in how they receive the use of certain features in email marketing, such as ALL CAPS and personalizations. Finally, we demonstrate that adjectives and adverbs are necessary parts of speech in marketing, but that using exaggerated examples of these may have negative effects on an email's open rate.