Making the Most out of Your Subject Line


The subject line is one of the smallest components of any email you send, but it’s also the most visible. In the case of an email marketing strategy, this matters more than you might think. Consumers face a barrage of branded emails every day, and because their time matters, they have to be choosy.

Think of your personal inbox. How many marketing emails do you receive on a daily basis — and how do you handle them? If you’re like most consumers, you pick a few to open and either ignore or mass-delete the rest. This isn’t a bad thing. It means you’re spending your personal time and energy wisely.

As a marketer, your carefully crafted email content carries no clout unless the reader opens the message. The best way make this happen? Optimize your subject line.

A Roundup of Subject Line Statistics

Depending on the sender’s industry, branded email open rates tend to fall between 15 and 25 percent. According to a recent Epsilon study, emails that feature the arts boast a click rate of 27.9 percent, while the rate for emails containing online coupons dwindles at a paltry 13.9 percent.

Aside from industry niche, a few different factors affect this click rate. One such factor is the recipient’s email client. Data from Litmus Labs tells us almost 50 percent of consumers view email on their mobile devices. The rest use webmail or a desktop program like Microsoft Outlook. Across the board, Apple email clients are most widely used.

Why does this matter? Well, because each email client displays subject lines in a unique way, the same unopened email can look completely different from one device to the next:

iPhone. The subject line character limit for portrait orientation is 38. For landscape orientation, it’s 80.

iPad. Regardless of orientation, the subject line limit for the original iPad is 39 characters. For later versions, including the iPad mini, the character limit is 41 in portrait and 64 in landscape.

Galaxy. When this Samsung device is held in portrait orientation, the subject line has a maximum of 33 characters. In landscape, the limit is 72.

Galaxy Note. The subject line has a limit of 34 characters in portrait and 12 in landscape. The smaller limit in landscape is due to the fact that the Note automatically splits the screen when the device is oriented this way. The split screen allows users to view their inbox on the left and compose an email message on the right.

Kindle Fire. In portrait, the character limit is 79. In landscape, the limit is 84. Like the Note, the Kindle Fire tablet splits the email screen when oriented in landscape.

Surface. In portrait, the Surface tablet has a character limit of 76. In split-screen landscape, the limit is 31.

Web browser. When you access your email account with a web browser, the apparent length of email subject lines depends on the size of the browser window — and, by association, the size and resolution of your device’s screen.

As you can see, individual mobile and desktop devices vary significantly in terms of allotted subject line characters. Marketers also need to take other iPhone and Android quirks into account. According to Kissmetrics, iPhone cuts off the subject line at the character limit, while subject lines on Android wrap around from one line to the next.

It’s a subtle difference, but it’s an important one. Take a look at the subject lines in the iOS interface, shown here:

And the Android interface, shown here:


With the stats in mind, it’s up to you to steer recipients in the right direction.

Optimization: It’s (Kind of) Subjective

There’s no such thing as a perfect subject line, but there is such a thing as an optimized one. If there’s one takeaway from the statistics outlined above, it’s that subject lines need to be short and to the point. The proof is in the pudding — or rather, in an analysis of email marketing data by MailerMailer. In terms of open rate, subject lines with as few as four characters (and as many as 15) outranked all the rest. Once you pass 15 characters, engagement drops significantly.


Of course, length is only one aspect of optimization. Another component is personalization. There’s a huge difference between receiving a generic mass email and an email addressed to your name. Researchers at MailChimp found subject lines that include the recipient’s first and last name had the strongest impact.

Personalized emails can serve a few different purposes, especially when they account for a user’s online history. For example, Amazon tracks visitor behavior and then sends triggered emails based on products they viewed.

Additionally, according to Business Insider, almost $4 trillion worth of merchandise is abandoned annually in ecommerce shopping carts. Instead of letting the abandoned items fall by the wayside, the intelligent approach would be to send a targeted email to the shopper. A subject header as simple as, “[Name], you still have [item] in your shopping cart” could mean the difference between conversion and oblivion.

Another way to optimize email subject lines is to include multiple topics. In the same way SEO often targets multiple keywords for the same landing page, an email subject header can provide multiple reasons to click. This is an especially good strategy for newsletters, where different article topics will appeal to different viewers.

However, it’s important to note that a strategy of multiple-subject topics directly opposes the above recommendation to stay within a strict character limit. You’ll have to conduct a few tests to see what works best.

How It All Comes Together

While getting a reader to open an email is only half the battle, it’s a huge step in the right direction. Ultimately, as a marketer, you’ll need to experiment with email subject headers to gauge what’s going to work for you. Statistics-driven optimization is a good start, but it’s important to keep track of your own analytics to get a sense of how consumers respond.

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