You can find articles aplenty proposing sure-fire ways to craft open-rate boosting subject lines — many even suggesting the right word-specific choices.

We’re going to help you brainstorm ideas a slightly different way: by showing you how easy it is to browse the real-life subject lines your peers, competitors and relevant industry groups are actually using today.

 

Basic rules of A/B subject-line testing

Before we begin, we’ll assume you know basic rules of A/B subject-line testing. For instance, you’re aware you must:

  • Test repeatedly (and with large-enough samples) to ensure your results are statistically meaningful
  • Limit your test to the subject line only — because testing multiple variables (e.g., images or headlines or CTA buttons) makes it nearly impossible to conclude with any confidence why one email has outperformed another

 

Start by browsing your competitors’ subject lines

Once you’ve signed up for a free MailCharts account, you can pick up to 3 peers or competitors whose emails you’d like to track. For each brand you track, Inbox view lets you browse their latest subject lines at a glance.

Let’s say you do email marketing for a luggage brand and have decided to track Tumi. Switch to Inbox View, and Tumi’s most recent emails and subject lines (with preheaders) are at your fingertips:

Tumi Inbox view 1024x712

You’ll notice that our inbox, like any regular email inbox, displays the preheader text along with the subject line. Around here we like to say that if your subject line is Batman, your preheader is Robin. It’s the sidekick you need to help get your emails opened.

Pro Tip: When testing subject lines, avoid complicating your results. Use the same preheader for all your variations.

 

Keep your subject line fairly short

You might also notice that Tumi’s subject lines are fairly short. In fact, your At a glance stats show they average only 32 characters:

Tumi At a glance view red circle 300x69

We judge that length to be inbox friendly. Why? Popular email clients like Gmail and Apple Mail can display only so many characters before they hide the rest of your subject line. And their rules can be even more restrictive for displaying subject lines (and preheaders) on mobile devices, where, incidentally, 40% of emails are opened on iPhones alone.

Pro Tip: Subject lines in your A/B test should run no more than 55 characters. To learn more, check out our Short Email Subject Lines blog post.

Let’s take a look at the email subject lines from another luggage brand — Samsonite:

Samsonite Inbox view 300x184

Right away you can see that Samsonite’s subject lines are much longer than Tumi’s — averaging an inbox-busting 81 characters. They also rely much more heavily than Tumi on promotional enticements (e.g., “48 Hour Flash Sale”):

Samsonite At a glance view red circle 300x74

What’s more, unlike Tumi’s, some of Samsonite’s subject lines employ emojis.

Do subject line emojis increase your open rate? It’s hard to find recent data proving they do, but our Advanced Search options show they’re still popular. We searched a recent two-week period and found that of the more than 113,000 emails we received fully 25,000, or about 22%, carried emojis.

Pro Tip: Testing subject line emojis offers an easy way to dip your toe into the A/B testing pool. Just be sure your emoji appears at the beginning or end of the line, so that email clients that fail to display them properly won’t disrupt the flow of your message.

 

Size up subject lines from multiple industry brands

Of course, if you work in marketing for a luggage brand, there’s an easy way to dig into email subject lines from 11 Bags/Luggage brands at once — including Tumi, Samsonite, eBags, Kipling and many more:

Bags Luggage Industry inbox view edited 300x192

In fact, when you open a MailCharts paid account, you can access subject lines, emails, reports and more from popular brands grouped across more than 68 industries, from Apparel and Air Travel to Fast Food and Footwear.

Along the way you might even spot a competitor’s A/B subject line test. For example, in the Bags/Luggage inbox above it’s clear Kipling tested Upping This Sale to 4 0 % O F F! against 40% OFF | You Are One Lucky Member! (Oops! It also tested different preheaders for both emails, making its subject line test results tough to evaluate.)

 

Check your thinking against our real-world subject lines

You can scan the web for subject line strategies to A/B test and find no shortage of ideas and advice. Just be sure to let MailCharts help you check your creative thinking against the real-world subject lines your peers and competitors are using in the wild right now.

Remember, too, that MailCharts scores all emails according to 8 industry best practices that include inbox-friendly subject line length (no more than 55 characters) and a related metric, mobile optimization. The iPhone’s email client, for instance, can display only 41 characters in portrait mode.

Testing subject lines can yield conversion-boosting results and be tremendous fun. To add some science to your creativity, turn to MailCharts data before you test.

Editorial Image by Gerd Altmann from Pixabay