We send emails every day, and a lot of them (email traffic will approach 200 billion messages per day in 2015, according to The Radicati Group), but no part of an email is so important, perplexing, and even overlooked as the subject line. Back in 2012, the Obama Campaign pulled off a textbook execution of a killer email blitz for fundraising, and afterward disclosed their famously brief, yet best-performing subject line, “hey.” Of course we all can’t simply emulate one instance of success, as an inbox of identical subject lines would be utterly maddening. However, we can look at some principles as to why certain subject lines are more effective than others. Indeed, whether you’re sending out a weekly newsletter or a new product announcement, it’s prudent to take a moment to appreciate the part-art, part-science that goes into creating an effective subject line.
Do It, and Do It First
The body of an email typically gets the most attention, and often to the detriment of the subject line. In fact, it’s not uncommon to leave it to the end of the email writing process (don’t worry, we’re all guilty of this). The subject line shouldn’t be an afterthought, as it’s the first thing a recipient sees, thereby setting the tone for the rest of the email. Furthermore, it can be more effective to write the subject line first to focus the message of the body content.
Rite for Mobile
Most people are aware subject lines should be (at least somewhat) brief–sentences need not apply. But how brief, exactly? Generally speaking, inboxes cut off at around the 60th character of a subject line, so the long-held rule of thumb has been to not exceed 50 characters, just to be safe. That rule of thumb might still be adequate for recipients checking emails on larger screens (desktops, laptops, netbooks), but inadequate for mobile checkers, who now comprise the majority.
While the estimates vary between just over half (53%, Litmus) to nearly two-thirds (65%, Movable Ink), there is ample evidence to confirm the majority of emails are now received and opened on mobile devices, and the trend will only continue in the foreseeable future. What can you do about it? Cut the “50 Rule” in half, as the cutoff for mobile inboxes is about 25-30 characters. Tailoring your subject lines for mobile inboxes will not only address a growing audience, but also encourage concise writing.
Don’t Get Wordy
It’s clear subject lines need to be shorter, so here’s how to cut them down. First, eliminate unnecessary words (i.e. filler words that don’t add clarity or words that can be communicated in the body of the email). Also, put the most compelling and the most important words at the beginning, though not at the expense of comprehension. This will not only act as a failsafe against character cut-offs, but also produce subject lines that get straight to the point. Lastly, subject lines are not de facto literacy expositions, so there’s no need to exercise your vocabulary, as robust as it may be. Longer words eat into the character count, so opt for short, easy-to-digest words. This last word-curbing suggestion also plays into the next consideration: subtext.
Between the Lines
There are two sides to every subject line. Its most obvious function is revealing information about the email, but it also reveals information about the sender in nuanced ways. Take capitalization: a subject line in title caps (“This Product Is Revolutionizing The Industry”) screams formality; lowercase (“what’s going on?”) screams familiarity; all caps (“TRY THIS NOW”) simply screams. Informal subject lines, written in a friendly format, offer an understandable appeal for recipients, and they tend to outperform formal or scream-y subject lines whenever they’re compared. Also influencing a recipient’s perception of friendliness is word choice, as hinted above. Plain vocabulary, mild slang, and even mild cursing can establish a sense of familiarity–the latter, of course, when implemented judiciously.
When it comes to indicating the content of the email, there are a couple of routes to take. An overly informative subject line cuts like a double-edged sword: it may give some recipients reason to open, while giving other cause to ignore. On the other end of the spectrum, an ambiguous “hey”-style subject line may peak a recipient’s curiosity, but if used too often its effect may be diluted. A common technique is initiating a kind of call and response–a question or phrase that engages the recipient and compels them to open the email (e.g. “Is your closet this clean?”). This middle ground, if you will, adds some indication of what’s in the email with out giving away the whole thing. Whichever direction you go with your subject lines, it’s important to test different tactics and use the data to make informed decisions.