Best Practices for Standout Email Subject Lines

Our top tips for writing subject lines that will keep your emails in the inbox.

top view of a lot of envelopes

An email subject line can either be your first impression or your last. It can be the difference between connecting with a subscriber and turning them off.

And today, the number of emails sent daily now exceeds 319 billion. As your subscribers scan their inboxes, you have only milliseconds to convince them your email is worth opening. Now more than ever, your subject line matters.

Here are evolved best practices for crafting inviting subject lines.

1. Emoji the possibilities

In the emoji age, you can ditch the formalities. While modern readers are more accepting of casual subject lines, a poorly chosen emoji can alienate readers. For example, a report by Experian found that 56% of brands had a higher unique open rate with emoji subject lines, but up to 44% saw a decline as well.

Say your marketing department is releasing a thought leadership survey that reveals a positive outlook for a profession; for instance, a small business association survey finds members are likely to expand their operations in the coming year. A sunglasses emoji next to few words connotes optimism:

[mock email subject line] Q3 small business outlook: ?

But it’s still important to keep your audience — and subject matter — in mind. The National Funeral Directors Association, for example, may not be the right target for bright emojis. And the email platforms your subscribers use play a part, too. Some versions of Outlook 2003, for example, don’t render emojis, which could mean a message lost in translation to a less tech-savvy audience. (For more guidance, check out Campaign Monitor’s handy chart of which email clients display emojis.)

2. Tease, tantalize — and then deliver

Yes, open rates matter. Yes, you want your content consumed. But the package needs to match the packaging. An eye-popping subject line works, but the content that comes after should fulfill the promise made.

Take some of Slate’s “thirstiest” subject lines from the 2020 Democratic presidential candidates as examples of what not to do. Senator Amy Klobuchar’s note to supporters titled “My last email” played on shock, urgency and scarcity to get readers to open. But the content didn’t back up the promise made to readers — it was her last email of the quarter, not the campaign. The result? A bit of trust lost.

In contrast, former Texas Rep. Beto O’Rourke sent out an email subject-lined thusly: “Banquet hall tilapia” — a callback to one of his speeches. Its weirdness and novelty enticed readers to open, and the content actually delivered.

One thing that hasn’t changed about email marketing: Avoid spam trigger words, which will Double your chances! of 100% turning off your readers.

3. Curb your characters

With the rise of mobile reading, the best subject lines are fewer than 40 characters. The 30-to-40-character rule is based on how a subject line displays on a smartphone, where most readers read their email now. Keep in mind that perhaps the best-performing subject line of all time was the 2012 Obama presidential campaign’s “Hey.”

For email marketing, subject-line brevity has practical implications. For example, though displaying your organization’s acronym appears to establish trust with your audience, it’s wasting valuable real estate — especially since the name already appears to the left of the subject line on a desktop or laptop or just above it on a smartphone.

Email template designer and coder Uplers (formerly Email Monks) suggests your subject line follow the 2-2-2 rule: it should catch your target’s eye in two seconds, convey your message in the first two words, and play on urgency to open the email today.

4. Boost your (artificial) intelligence

A human touch can still crack the toughest inbox. But the rise of AI has turbocharged email marketers’ ability to personalize their approach to connecting with readers, including with optimized subject lines.

[mock email subject line] Happy Friday, Adam! ?

According to Accenture, AI is expected to deliver $14 trillion in additional revenue for companies by 2035. Futureproof your marketing approach by taking advantage of that trend. AI can harness data about your subscribers and personalize renewal pushes and member benefit drip campaigns. It can also now create drip email campaigns that use brand-friendly words to break through the digital detritus of any subscriber’s inbox.

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