Choose Them Wisely: How Words Affect Email Open Rates

Are your subject lines helping or hindering your email open rates? To find out, we looked at two pieces of research that drill down into the details of what makes an email subject line irresistible to readers.

The first is a whitepaper from email data solutions provider ReturnPath that analyzes the performance of common keywords in email subject lines. The report found that words that subject lines that express "Urgency" performed the best, followed by "Benefit" and "Command" (those that tell the reader what to do).

Surprisingly--and perhaps happily for those of us sick of seeing them--"Clickbait" type subjects (e.g. 3 Things Realtors Should Never Do. #2 Will Shock You!) performed poorly. This doesn't mean that they're ineffective on other channels, like social media or blogs, but it does indicate that you should think twice before crafting your email subject lines in that style.

Below is a brief sampling of how different keywords performed. The numbers indicate how that word impacted the open rates when compared to other subjects lines from the same brand.

Benefit Keywords

Superlatives seem to perform well in subject lines--but you have to be careful about which you choose. While email recipients love things that are the "fastest," they're much less enthusiastic about things that are "quickest."

• Fastest: +5.3%
• Prettiest: +2.87%
• Cheapest: -2.94%
• Quickest: -2.01%

Clickbait Keywords

Save the drama for your mama, not your subject lines. Words that play to scandal don't impress readers, and even the ones that do perform positively still only get a "meh" reception.

• Secret of: -8.69%
• Shocking: -1.22%
• Won't Believe: -.034%
• What You Need to Know: +0.62%
• Get Rid of: 0.83%

Command Keywords

"Register" was one of the highest performing keywords in the study, so perhaps agents shouldn't fear encouraging consumers to register for their IDX site to receive listing alerts or other benefits! On the other hand, the data suggests that a hard approach to sales (using the word "buy") is a no-no.

• Register: +6.7%
• Open: +1.73%
• Add: 1.13%
• Buy: -1.25%
• Put: -1.50%

Pronouns

Who's the, well, subject of your subject line? While pronoun selection didn't have a huge impact on open rates, the only pronoun that performed positively was "you." So if you're going to use pronouns in your subject, make sure that they're focused on the reader, not you.

• You: +0.10%
• Mine: -1.69%
• It: -0.48%
• Me: -0.2%
• I: -0.12%
• Our: -0.26%

Urgency Keywords

Creating a sense of urgency is a classic sales technique. ReturnPath's analysis shows that it's still an effective way of grabbing people's attention.

• Still time: +15.54%
• Limited time: +3.05%
• Expiring: +1.63%
• Running out: -3.3%
• Extended: -2.95%

The paper also noted that "steps" performed well (+1.23%). Realtors looking for a way to apply this bit of information should consider using this word as a way to share guidance, e.g. Steps to Qualifying for Your First Mortgage, etc. This is especially handy for agents who serve a lot of first-time buyers.

This is just a sampling of the words analyzed in the report. For a more extensive look at how keywords perform, read the full whitepaper.

A Brief Note on Subject Line Length

Email marketers are often told to keep their subject lines brief, but an analysis of over 9 million subjects suggests that this advice may be misguided. As you can see in the chart below, subject lines of 61-70 characters performed the best, followed by subjects with 91-100 characters.

While there are benefits to shorter subject lines--they're friendlier for mobile users, for example--agents shouldn't shy away from lengthier ones. That doesn't mean you can ramble on; just remember that carefully worded email subject lines can have a big impact on how recipients perceive you and your message.

Your turn: Agents, what subject lines have you used most successfully? Which ones have failed?