4 Email Subject Line Myths We Need to Stop Believing Now

Whitney Blankenship
6 min read
Dec 20, 2018
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Email subject line myths

Researching email subject line trends is a huge part of making sure we keep up with the best practices. One of the biggest problems is when “best practices” fall out of trend before anyone really catches on.

We studied all emails sent from the Omnisend platform in 2017 to see which lines worked the best and we discovered a few “best practices” that maybe aren’t actually the best.

There are 4 main email subject line best practices we’ll be examining today:

  1. Personalizing an email subject line with your customer’s first name improves open rates
  2. Adding exclamation marks improves open rate by adding a sense of urgency- the more the better!
  3. Percentages work better than dollar amounts in subject lines
  4. Your subject line should be as short as possible for the best open rates

Let’s find out if these best practices are in line with our latest research!

Myth #1: Personalizing an email subject line with your customer’s first name improves open rates

Personalization, when we’re talking about email subject lines, usually refers to the practice of adding the recipient’s first name to the subject line.

Oft touted as a “best practice” in email marketing, we wondered if our research showed any correlation between personalized subject lines and open rates.

In my opinion, first name subject lines have fallen out of vogue and can even seem spammy (perhaps because they’re unrealistically personalized, since I know it’s a company and I know it’s automated), while my colleagues had differing opinions.

Apparently, personalized subject lines have lost steam with retailers as well: only 3.5% of all emails we analyzed had a personalized subject line.

When comparing open rates for those emails, we found that personalized email subject lines only had a 0.2% increase in open rates. Emails with a subject line containing the recipient’s first name were opened at 18.1% on average against 17.9% of those that didn’t.

The data shows that not only are personalized subject lines losing popularity, but they’re not even more effective.

Myth #2: Adding exclamation marks improves open rate by adding a sense of urgency- the more the better!

We compiled our 30 most successful email subject lines for newsletter campaigns, and we noticed that nearly half of the top subject lines contained an exclamation mark.

We began to wonder if including an exclamation mark in subject lines would have an impact on open rates. We decided to break this down into two separate categories: newsletter campaigns and automated email workflows.

Newsletter Campaigns:

For newsletter campaigns, use of an exclamation point was split down the middle: 42% of all emails sent had subject lines with the punctuation mark.

We saw that subject lines without exclamation marks did slightly better than those with them: subject lines without exclamation points measured an 18% average open rate over 17% open rate for subject lines with them.

In fact, the more exclamation marks there were, the lower the open rate was. Average open rates for subject lines with 2 exclamation marks came in at only 16.7%, and if a third exclamation mark was added, the open rate dropped to 16.5%.

Automation Workflows:

We then decided to look at how exclamation marks affected open rates for automated workflows. Adoption of this punctuation mark is much higher for automated flows- 95% of the automated emails Omnisend marketers sent out contained exclamation marks.

Not only is adoption higher, but open rates were much higher as well. We found that email subject lines containing one exclamation mark were opened at 29% on average, while subject lines containing 2 or more were opened at 35%.

We have to take these numbers with a grain of salt as there is a significant difference between having one exclamation point and having two.

We saw some other interesting results from our analysis when we broke it down even further into single vs multiple email workflows.

Single-Email vs Multiple-Email Automated Workflows:

Automated emails with just one exclamation mark had a 47% open rate, but adding more dropped open rates to 42%.

When sending multiple automated emails in a workflow series, more exclamation marks also had a negative impact. Multiple email sequences with subject lines containing one exclamation point had a 24% average open rate, while subject lines containing more than one had only a 21% average open rate.

The total verdict? Using an exclamation point can work depending on the kind of email you’re sending. However, less is usually more.

Myth #3: Percentage discounts work better than physical dollar amounts for open rates

$15 dollars off? 15% off? Which format works better to get that email opened?

We decided to analyze our subject lines to see if physical dollar amounts or percentages worked better for discounts. With the popularity of percentage signs, we can tell what the myth is here.

10x as many marketers used the % sign in their subject lines vs those that used the $ sign. Nonetheless, the $ sign does better in terms of open rates.

Subject lines that contained the $ sign had a 29% average open rate compared to the 25% average for subject lines containing the % sign.

This success might be due to the fact that so many more marketers are using % discounts in their subject lines that the $ sign stands out. Nevertheless, it’s a good idea to experiment with using dollar amounts in your subject lines.

Myth #4: Keep your subject lines as short as possible for the best open rates

The last thing we really noticed when analyzing our email subject lines is that we had one brand that loved to use long subject lines.

This one has 213 characters:

“COMING SOON: Adidas Originals Equipment Support EQT "White/Turbo-Red" Pack & EQT Support BOOST Ultra "Chinese New Year" / Stussy - Spring/Summer '17 Collection / New Balance - 247 & Sport Style Clothing Collection”

Naturally, we wondered how the length of subject lines affected open rates. The average subject line we analyzed had between 11 and 50 characters.

Despite being the most frequently used, subject lines between 11 and 50 characters didn’t have the best open rates.

Actually, subject lines with character counts between 51 and 90 characters had a 40.5% average open rate, while the most frequently used length of 11-50 characters had an average of 33.8%.

It’s important to note that because of the popularity of the 11-50 character length for subject lines, the sample size of the 51-90 range is much smaller.

The sweetest spot? Subject lines between 21 and 30 characters have the best average open rate. Keep your email subject lines in this range for the best results on your next campaign.

Don’t believe in subject line myths!

Studying email trends is what keeps us up to date with how our customers are reacting to our campaigns. While we try to keep up on best practices, it’s important to always check new research to see if the best practices are still really the best.

These results could be, as previously mentioned, a result of exposure. When we change things up and we do it a little differently, we are able to better capture our customer’s attention.

Whether it’s a subject line with eight exclamation marks or 150 characters, it’s always crucial to test various methods to see what works best for your customers.