How to Write the Perfect Ecommerce Email Subject Line

Danny Wong

2. Email subject line rules

Contents

To conjure up what you believe to be the perfect email subject line, remember to follow these five golden rules of email marketing. Hopefully what you come up with is so compelling that you will automagically prompt an open.

1. Deliver emails to opt-in lists only

When consumers see a promotional email from an organization that they have not opted-in with, it can potentially do more harm than an email that is ignored: they may resent the very act itself. While it may seem burdensome, creating an opt-in campaign is a great way to both update your distribution lists with valid emails and restate your value proposition to the customer.

2. Carefully consider subject line length

Length is one of the most important factors involved in writing effective email subject lines, and it leaves many business owners flustered in their attempt to convey value in such a small amount of space. It is a tricky thing to get right (just look at how many people are bad at writing interesting tweets), but unfortunately, those are the breaks. You have to be able to clearly give your reader a reason to open the email without the subject line running so long that a viewer’s email client crops the end.

Of course, the appropriate length of the subject line depends completely upon the size of the screen your recipient is using. In general, laptop and desktop screens will accommodate 50 to 70 characters in length, while most mobile devices are limited to approximately 25 to 40 characters. In CM Commerce’s latest analysis of email opens, we found that there is nearly a 50/50 split between desktop users and mobile & tablet users (combined).

  • Desktop users account for 48.00% of all Ecommerce email opens.
  • Smartphone users open 46.03% of all the emails sent through the CM Commerce platform.
  • Tablet users are responsible for the remaining 5.97% of Ecommerce email opens.

Therefore, to err on the side of caution, you may want to be more conservative with your email subject line length. That said, a length of five to seven words is probably your best bet for presenting a complete subject on the screen and avoiding cropping. If you can write something compelling that is even shorter, it may help you stand out in a crowded inbox.

  • Across 6,407 unique receipt templates, we found that the:
    • Shortest email subject line was 4 characters long
    • Longest email subject line was 363 characters long
    • Median email subject line was 38 characters long
    • Average email subject line was 38.67 characters long
  • Across 4,511 unique Follow-Up email templates, we found that the:
    • Shortest email subject line was 5 characters long
    • Longest email subject line was 142 characters long
    • Median email subject line was 33 characters long
    • Average email subject line was 38.25 characters long
  • Across 2,984 unique abandoned cart email templates, we found that the:
    • Shortest email subject line was 6 characters long
    • Longest email subject line was 96 characters long
    • Median email subject line was 32 characters long
    • Average email subject line was 35.27 characters long

The other issue you need to be aware of in terms of length is the possibility of cropping leading to the creation of an offensive word on the reader’s screen. For instance, our in-house email marketing expert, Becs Rivett-Kemm, recalls, “I’ve seen an email subject line that read ‘2 for 1 cocktails’ and it got cropped… yeah you can guess what happened.” She also points to a tweet by Ecommerce marketer Dan Barker which shows how senders can face a similar issue with their display name.

These are both useful demonstrations of what can happen when you are not careful. Therefore, it is always best to send yourself a test email first and view it across different devices.

3. Conservatively use capitalization and punctuation

Many people think that the reduction of proper use via text and other messaging services has made it acceptable for companies to be lax on their own application. It is certainly true that many younger consumers have grown up in a world with fewer capitalized words, nonexistent punctuation (save for numerous exclamation marks following “OMG”), and contractions without apostrophes, but that does not mean it is effective to ignore the rules of grammar.

Firstly, you can never be certain that your message will be received positively. While someone who is comfortable with not using proper capitalization and punctuation is not likely to be put off by its presence, the reverse is absolutely true. People who care about grammatical rules are unforgiving when someone has broken one. It is just good practice to capitalize the first word in your subject line and any proper nouns within. Also, use appropriate punctuation: periods are not necessary for single-sentence subjects because they act as a title, but you should use a single exclamation point or question mark if the situation warrants. Keep in mind too that using a string of exclamation points does not generate additional excitement; it only makes the sender look unprofessional.

4. Apply power words

Word choice is a powerful tool for email subject lines, and there is evidence to indicate that certain words have more of an effect than others within a specific industry. These are often called “power words,” and finding ways to use them strategically can have a significant impact on both your open rates and reply rates. However, it is important to note that just because a word appears frequently does not necessarily mean that it is higher-performing than others.

One easy strategy for discovering potential power words in your industry is to take a cue from your competitors. Sign up for their email lists and pay attention to word trends as you receive their marketing material. If they are deliberate with their email marketing copy, they will surely insert power words frequently in their subject lines. Do not take this to mean that you can just copy them, however. You have to devise original and creative ways to use these power words so you do not risk coming off as an imitator to your potential customers.

When we reviewed the 7,246,557 Follow-Up emails Ecommerce store owners and marketers had delivered through the CM Commerce platform, we were able to generate a list of power words that heavily influenced open rates. Below, we have the 10 best words to use in your next email subject line and the 10 worst. Keep in mind that among our Follow-Up emails, the average open rate is 41.95%, so simply adding the word “thanks” to your next email could possibly increase your open rate by more than 50% (~24 percentage points).

5. Be mindful of spam trigger words

And just like there are power words that can increase audience response simply through their presence, there are also words that will instantly trigger a recipient’s spam filter and render your effort useless. Software engineers are creating more effective spam filter technology all the time, so it is important to stay up-to-date on the latest best practices regarding avoiding spam trigger words.

At the outset of any email campaign, you need to consult lists of possible spam triggers, such as this one, and consider which ones should be removed from your subject lines. These may play a role in marking your message as spam, but it is important to remember that contemporary spam filters place greater weight on the sender’s reputation and previous engagement with the user than on specific word triggers.

Looking for spam keywords is necessary, but you likely have some breathing room if you have already been established as a reputable sender in your recipient’s inbox.