Great subject lines for promotional email marketing messages have long been key to driving engagement, but with consumers’ inboxes being overwhelmed with undifferentiated COVID-19 updates, they’ve become even more important.

Looking at data from email intelligence company MailCharts, 17 out of 50 sample apparel brands sent emails between March 11–16 with some variation of “A note/message/update to our community/customers” — with no mention of coronavirus/COVID-19 or any specific actions in the subject line.

The basic tenet of a good subject line is that it does double duty. It tells the recipient specifically why they should open the message and sets up what action they might take after opening the email. With so many brands seemingly forgetting best practices at the moment, we wanted to remind marketers of great subject line basics.

New rules for a new world

Before diving in, it is important to recognize the moment we live in and how that affects content, including email subject lines.

Trust: Now more than ever, consumers are seeking brands they can trust so avoid over promising, exaggerations, or resorting to trickery.
Tone: Be empathetic, help solve consumers’ current and most pressing needs, and avoid humor unless it is a significant and recognized element of your brand.
Context: The COVID-19 pandemic is evolving almost daily and how consumers are being affected (directly or indirectly) can vary quite differently by market and demographic. Make sure your subject lines can stand the test of time (at least in the near term) and recognize that some content may not be relevant to segments of your subscriber base.

10 generally accepted subject line best practices

While these best practices are a good starting point, it is important to have a process for continuous testing and learning to determine the best approach for your individual brand.

Consider sub-branding: You could include a product, sub-brand, or newsletter name at the beginning of the subject line when you use the same “from” name for multiple message streams.
Length: Research several years ago from email marketing agency Alchemy Worx revealed that length can affect recipient actions in different ways. In their analysis, subject lines under 60 or more than 70 characters generate the highest response — but these ranges produce different results:
- Shorter subject lines generate higher open rates, but much lower click-to-open rates
- Longer subject lines have a much higher click-to-open rate, an indication of actual relevance and driving people to take action
- The open rate and click-to-open rate curves intersect at about 60-70 characters, a “dead zone” where neither metric is optimized.
- The general lesson is that longer subject lines with more detailed information lead to higher click-through rates — the ultimate goal for most email campaigns. If, however, your email has self-contained or very short content with no call-to-action, then shorter subject lines may be the best approach.
- Regardless of the approach, it is always advised to include key information within the first 40 to 50 characters so it displays on virtually all mobile device email clients.
Be creative: While humor during the current environment is probably best avoided, you can use personality consistent with your brand. Test using emojis or different types of copy and phrasing. If your audience is young or tech savvy, for example, you’d be able to use social media slang and acronyms (e.g., FOMO or YOLO).
Start early: One of the common mistakes email marketers make is to put off subject line creation until the last minute. Don’t. Start developing potential subject lines as you develop the message copy and images. As deployment, product, marketing/e-commerce, and creative teams collaborate — copy and images might be revised to better support the direction of a great subject line.
Focus on “the one thing”: Email marketing messages often contain multiple products, offers, and content that various constituents in your organization have a stake in. This frequently results in subject lines without a specific focus such as “15% off cycling apparel.” Better is something like: “15% off all jerseys and shorts from (a specific brand).”You might be “picking winners,” but if the goal is to maximize revenue this will generally produce a higher conversion rate. A way to address internal politics of course is to personalize these subject lines based on preferences or past purchases.
Urgency: Use dates, deadlines, and a sense of scarcity to help motivate recipients to take action.
Personalize when possible: Personalize subject lines with targeted content based on preferences, demographics, location, weather, and especially behavior.
Avoid being “spammy”: Never trick or mislead just to inflate open rates. This will ultimately destroy trust with recipients, damaging your brand, and drive customers away. Generally, avoid using all capital letters, multiple exclamation points, and overly aggressive copy that might annoy recipients or get a message to be flagged as spam. Do, however, use action words designed to drive recipients to take action.
Be contextual and timely: Leverage topics in the news, cultural events, and customer lifecycle stages for creativity — be careful that you don’t offend segments of your subscriber base.
Test, test, test: Before testing subject lines, analyze your previous sends and see what, if any, trends you can identify that drove higher open, click, and conversion rates. Use this analysis to help drive what you want to test going forward, such as length, copy style, personality, use of incentives, or product brand names. Have a plan to test a number of subject line variables progressively so that at some point you have a strong sense of what works best with your subscribers — length, personality, offers, etc.

The basic tenet of a good subject line is that it does double duty. It tells the recipient specifically why they should open the message and sets up what action they might take after opening the email.

One last reminder: subject lines with lower open rates frequently result in more actions and higher conversions and revenue. So when measuring the impact of your subject lines, don’t rely just on open rates. Include a wide range of metrics to determine which ones and types are most effective for your brand such as conversion or click-to-open rates.

Check back often as Acoustic continues its series of Brilliant Basics marketing practices.

Email marketing subject lines: 10 tips for better engagement

Related Insights & Enablement