Skip to content
Start Free Trial Now
Email subject line best practices
Ashley GrantFeb 23, 2024 4:55:09 AM8 min read

Worst and Best Practices for Email Subject Lines

Are you using the best practices for email subject lines? If you can’t answer this question with a quick yes, this post is for you.

There’s a reason that email subject lines are talked about so much on marketing websites. It all boils down to one simple truth - A bad email subject line can ruin your email campaign results.

We don’t want your email subject lines to fall flat. So, with that in mind, let’s explore some things you should and shouldn’t be doing.

Why Email Subject Lines Matter

Your email's fate hinges on an optimized subject line. When done right, compelling subject lines have an outsized impact on email performance. Here's why you should pay attention to crafting killer subject lines:

Sky-High Open Rates

A magnetic subject line dramatically lifts open rates. Studies show that subject lines influence whether 64% of readers open an email. Using the right techniques can double, or even triple your open rates. Imagine if hundreds more people opened your emails by tweaking a few words.

Inbox Attention Grabs

Inboxes are more crowded than ever. The average office worker gets 121 emails per day. That means your subject line has two seconds to catch your reader's eye amongst the flood. Using emotional and benefit-driven subject lines ensures your email gets noticed.

Optimization Opportunities

Well-crafted subject lines offer optimization opportunities at every step. Compelling subject lines lift open rates, click-through rates and conversion rates. Continually testing and refining based on performance data means you can substantially improve email results.

The headline sets the stage for email success. Spend time crafting stellar subject lines, and your emails will convert more readers. Keep reading to learn techniques to avoid and best practices to implement.

Worst Practices to Avoid with Your Email Subject Lines

Many common subject line tactics actually deter opens and clicks. Steer clear of these worst practices so your emails get the attention they deserve. Here are subject line approaches that tend to backfire:

Misleading Urgency

Creating false urgency or scarcity usually falls flat. Lines like "Act Now!" or "Limited Time Only!" won't fool savvy inbox-skimmers. Overusing hype trains readers to ignore real offers. Use urgency carefully only for legitimately time-sensitive content.

Repetitive Redux

Sending the same subject line multiple times annoys recipients. Changing just a few minor words also reads as repetitive. Frustrated subscribers may unsubscribe or mark emails as spam. Always create fresh, specific subject lines tailored to each campaign.

Missing Relevance

Forgetting personalization and relevant details is a missed opportunity. Generic subject lines written for a faceless audience flop. Laser focus on what matters to different reader segments for higher relevance and response.

Spam Trigger Words

Well-intentioned subject lines can accidentally trigger spam filters. Try avoiding spammy phrases like "Earn Cash Fast," "Lose Weight Quick," and "Free Gift". Analyze subject lines that end up in spam folders, then optimize language. Sending test emails to an internal test group is a good way to figure out if your emails are landing in the SPAM folder, and this tactic can come in especially handy if you are running a business that is prone to being subject to some prejudice, like iGaming or Crypto for instance.

With a little extra thought, you can ditch distracting tactics in favor of compelling lines. Next we’ll cover subject line best practices with proven performance.

Best Practices to Implement with Your Email Subject Lines

Now that we've covered pitfalls to avoid, let's focus on proven best practices for stellar subject line performance. Use these strategic techniques to compel more opens, clicks and conversions.

Laser-Focused Personalization

Dynamic subject lines personalized to each recipient convert best. Merge first names, locations, past purchases and more into your lines. Segmenting audiences also allows ultra-targeted subject lines based on behaviors and demographics.

Intriguing Numbered Lists

Subject lines featuring numbered lists consistently shine across industries. Lines like "6 Ways to Slash Monthly Bills" and "3 Reasons to Upgrade Your Yoga Practice" are hard to resist. List-based subject lines imply quick value readers won't want to miss.

Power Words That Pop

Certain words proven to lift open and click-through rates can optimize subject lines. Words like "Unforgettable," "Instant," "Mistake," "Exclusive," and "Secrets" build curiosity and urgency. Place power words front and center for maximum impact.

Emotional Triggers

Subject lines triggering excitement, laughter, curiosity and even outrage often succeed. Amusing lines utilize surprise or irony while serious lines evoke inspiration or controversy. Align dominant emotions with target audience values for boosted response.

Current Events Hooks

Leveraging current events in your subject lines grabs attention amidst overflowing inboxes. Mentioning the Olympics, elections, or pop culture phenomena intrigues readers. Ensure the content delivers on the timely promise.

Emojis for Stop Power

Strategically placed emojis in subject lines can lift open rates. A celebratory party emoji or love-themed heart work well for lifestyle content. Research ideal emoji use for your audience and platform.

A word of caution for emojis though - don’t over do it! One or two strategic ones will increase open rates. Any more than that and bam! It’s a ticket to spamville!

Bracketed Sender Info

Clearly branding sender information builds reader trust. Many brands place company names in brackets i.e. [Amazon], [Walmart]. Consider adding category information like [Electronics Deals] or [Apparel Promos] for added context.

Ultra-Specific Numbers

Odd or unexpected numbers in subject lines pique curiosity by standing out. Rather than round figures, highlight distinct counts like "13 Little-Known Facts" or "9 Shocking Predictions." Hyper specific stats feel intriguing yet credible.

With research-backed techniques in your toolkit, the sky's the limit for your subject line results. Continually test new formats while tracking performance data to determine what resonates best with each audience and campaign.

Subject Line Length and Timing Optimization

Beyond wording and messaging, optimizing technical elements boosts subject line performance. Factors like length and send-time significantly impact email results.

Finding the Right Fit

Determine ideal subject line length for each platform. Character limits span from 30 characters for SMS, to 100 for mobile push notifications, up to 150 characters for email. Know constraints, then make every character count.

Analysis by Day and Time

Pay attention to performance data fluctuations based on day-of-week and time-of-day. Weekday afternoons often have higher open rates as audiences check emails during work breaks. Promotional subject lines also thrive on Tuesdays and Thursdays more than other days of the week.

Iterate Based on Insights

Continuously test and analyze subject line length and timing data, then optimize. Suppose subject lines under 90 characters open better for your audience. Or promotional emails get more love on Wednesdays rather than Fridays. Tweak future campaigns accordingly.

With a research-backed framework established, diligently focus on fine-tuning subject line essentials over time. Next we'll take a look at why testing different versions is critical for ongoing optimizations.

A/B Testing - The Key to Ensuring You’re Doing the Right Things

Think you have a killer subject line? The proof is in the data. That's why continually subject line testing different versions is vital for optimizations.

Trying Multiple Variants

Instead of guessing which subject line will perform best, let the data decide. Craft several variants highlighting different copy, offers or formats. Send evenly split test groups the different subject lines to determine a winner.

Parsing Performance Metrics

Pay attention to how test subject lines influence open rates, click-through-rates, bounce rates and goal conversions. If a variant nets 20% more clicks for the same number of sends, you have a champion. Tracking downstream metrics shows true impact.

Iterating Based on Learnings

Use learnings from previous A/B tests to inform future ones. Suppose personalized subject lines sent on Thursdays converted 10% higher for women in Atlanta. Try localizing lines for more subscriber segments on that day.

A/B testing subject lines takes a bit more effort yet yields impactful optimization insights. The small upfront time investment pays off exponentially in the form of higher-converting email campaigns long-term.

Are You Using Great Email Subject Lines?

We've covered quite a bit of ground on the essential yet under-appreciated email component - the subject line. Now you know which worst practices to avoid that sabotage performance, as well as strategic best practices to deploy for stellar results.

Stay Clear of Pitfalls

As a review, common subject line pitfalls covered include using misleading urgency claims, sending repetitive copy, forgetting personalization and relevance, and inadvertently triggering spam filters. Steering clear of these issues ensures professional, optimized subject lines.

Implement Optimization Techniques

Conversely, smart techniques offer shortcuts to higher-converting subject lines. Personalized dynamic content, numbered lists, power words, emotional triggers and current event hooks compel opens. Fine-tuning length, timing and continuously A/B testing also boosts subject line performance.

The Power Is Yours

Equipped with a framework highlighting what to avoid alongside tactical tips for lifted response, the tools are in place to create stellar subject lines. It merely takes intention and consistent application of the principles shared here. Optimize your future email subject lines, then watch your open, click and conversion rates rise.

Now that you have the best practices for email subject lines in your toolbelt, what will you do next? We’re hoping your first step is signing up with SendX. After all, you need an awesome email marketing platform in your corner to send out all those amazing pieces of correspondence. Click here to get started with us for free!

Make Your Email Marketing Profitable