How to Write a Great Subject Line For Your Newsletter

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As one of your subscribers scrolls through their inbox, looking through the emails they’ve been sent that day, they’re always asking two questions:

• Who is this email from?
• Did they give me a reason to open their email?

The subject line is your answer to that second question. It’s your opportunity to catch a reader’s eye, to tell them: This is why you should take a moment to focus on what I have to say.

Writing a great subject line is harder than you’d expect. Subject lines should be a little like fingerprints: unique to you and the emails you’re creating. There’s no right way to write one — it’s up to you to figure out what your subject line style should be.

Subject lines are also the one place in the inbox where I see email senders implementing shady tactics to try to trick a reader into opening their newsletter. So before we get into best practices and tactics for A/B testing to optimize your subject lines, let’s talk about what not to do — because there’s plenty we can learn there.

Make sure you don’t sound like a spammer

Once, I got this email in my inbox from a sender I didn’t recognize, and the subject line was “You just made a real impact!” It seemed like the kind of email that would be tied to a donation — except that I couldn’t recall making a donation to any charitable organization that day.

But then I looked a little closer at the preheader text, and it mentioned… pizza?

It turns out that I’d gotten this email because I’d bought a pizza online, and the local pizza place’s online ordering system was powered by a third-party app that helps process payments for restaurants. The company that owns the app isn’t a mission-driven organization — they help local pizza places sell more pizza.

And let’s be honest: I didn’t make any sort of impact by ordering a pizza. This wasn’t an act of generosity. I didn’t raise money for important medical research, I didn’t donate blood, I didn’t volunteer my time. I ordered a pizza.

So why write an email with this type of subject line? Over the years, I’ve noticed that emails that congratulate or thank a reader often get high open rates. And understandably so: If you’re looking through your inbox, the email that screams “You’re amazing!” is the one that probably gets opened. 

But don’t be this type of sender. Some brands like to send subject lines that look like they were written by a friend or colleague, which can trick a reader into opening the email. Here are a few subject lines that landed in my inbox recently:

• hi 😉
• FWD: Did you see this?
• hey i’m on the zoom

Subject lines like this get written because the sender will do absolutely anything to get their email opened. But here’s a good rule: Before you send an email, go to your spam folder. If you notice an actual spammer using the same sort of subject line that you’ve written, that’s a sign that you should strongly reconsider your strategy.

Yes, emails like this do get opened. Opens don’t mean that the reader will engage further with your brand, though. If the email itself doesn’t match up with the tone set by the subject line, readers are going to get frustrated, and are far likelier to delete the email or mark it as spam. Sending subject lines like these is a great way to land yourself in the spam folder for good.

Five rules for writing a good subject line

While there’s no right way to write a subject line, there are a few rules you should keep in mind as you’re writing one for your email:

Rule #1: Set the tone for your email — Your subject line is your first chance to introduce whatever’s in that day’s email, so make sure it matches the tone of the message. It’s jarring for a reader, for instance, to see a fun, playful subject line, and then to open the email to see content inside that’s serious or somber. From the subject line alone, a reader should have a sense of what they’re about to get into.

Rule #2: Deliver on your promise — When I worked at BuzzFeed, we defined clickbait in a simple way: Clickbait was any story that didn’t deliver on the promise of the headline. If your headline said, “This is the Most Adorable Video of a Baby and Dog You’ll Ever See,” you’d expect the average reader would watch the video and go, “My goodness, that really is the most adorable video of a baby and a dog I’ve ever seen!” Anything less than that was clickbait. The same thing is true with your subject line. If you’re promising “Our best deals of the year!” in the subject line and then offering the same 10% off coupon code a user would get on your site, you should rethink your subject line. Don’t overpromise and underdeliver — your readers deserve better than that.

Rule #3: If you’re not sure what to write, just be direct — Email is for action, so if you’re stuck between a few options, choose the one that gives readers the action you want them to take. For instance, when trying to win back a disengaged reader, I’ve tested out lots of different subject lines, but I’ve never found a subject line that performs better than, “Do you still want emails from us?” It works well because it’s so direct. The user knows exactly what they need to do when they see this — they need to open the email and confirm whether or not they’re interested in receiving additional newsletters. If there’s an action you want a user to take, spell it out in the subject line.

Rule #4: Be consistent with your subject lines — Imagine for a moment that you’re the kind of person who wakes up every morning and turns on the local news to start your day. (If you’re already this kind of person, then feel free to be yourself for this hypothetical.) Every day, the broadcast begins with the news station’s theme music. But then one day, you turn on the news, and instead of that theme music, you’re greeted by the theme from “Benny Hill.” You wouldn’t feel entertained — you’d be confused. And that’s what happens if your subject lines change too much from day to day. You don’t want to startle your readers. Be consistent with your subject lines, and you’ll be able to build a consistent reading habit with your audience. 

Rule #5: Don’t worry about spammy words — Including a word like “discount” or “urgent” in your subject line isn’t going to land your email in the spam folder. (Resident deliverability expert Yanna-Torry Aspiraki can explain why.) Write the subject line you want — even if it does include one of those so-called spammy words.

Rule #6: Don’t forget the preheader text — There’s one more rule to keep in mind, and it might be the most important subject line rule of all: Don’t forget to include preheader text.

The preheader, or preview text, is what appears after the subject line in most email clients. Brands that use the preheader see open rates up to 15 percent higher than those that don’t — so if you’re not using it, you’re missing out on an easy opportunity to get more readers.

And here’s the thing about the preheader: If you don’t insert preheader text, the email client will do it for you. Have you ever looked through your inbox and seen newsletters that looked like this?

Those are brands that didn’t include a preheader, so that subscriber’s email client automatically grabbed whatever text led off the email — something like, “No images? Click here to view in your browser” — and showed that instead.

The preheader gives a subscriber one more reason to open your newsletter. You can use it to give readers more context about whatever’s in the subject line. For instance:

Subject line: It’s our biggest sale of the year!
Preheader text: From clothes to cookware, everything in our store is 35% off — but only for the next 24 hours!

Or you can tease a secondary item inside the newsletter:

Subject line: It’s our biggest sale of the year!
Preheader text: Plus, are you thinking of getting away this summer? We’ve got a few ideas for destinations you’ll love.

Together, the subject line and preheader should catch a reader’s eye and inspire them to open your email that day.

Find the right voice for your subject line

I’ve worked in-house on email at two very different companies. At BuzzFeed, we used emojis all the time. It made sense for BuzzFeed to have a subject line that simply said “😂”, as long as we made sure to feature a funny story as the lead piece in the newsletter, and as long as we gave readers a bit more context via the preheader about what they were going to see if they opened the email. We also used plenty of emojis inside the email — again, it was BuzzFeed, so using emojis (and slightly-offbeat GIFs) was on brand for us.

But at The New Yorker, emojis were definitely not our brand. In my time there, I can only recall using an emoji twice — both times in our humor newsletter. One went out on Valentine’s Day; the other, after a heavily-redacted intelligence report was released, and the day’s cartoon poked fun at the news:

Daily Humor: 💘 Is In The Air

Daily Humor: Trump Is ⬛️ ⬛️ ⬛️ Innocent

Understanding your brand’s voice is crucial to understanding what might be appropriate for a subject line. If your brand is fun or whimsical, sure, emojis or humor in a subject line might make sense. But otherwise, you risk looking a little clueless.

Here are a few more brands that do a great job with their subject line strategy:

Punchbowl News is a Washington, D.C.-based news organization that covers politics, and they’re focused on delivering scoops and inside information for their audience. They’re also one of the newer players in D.C. politics, and their style is more accessible and personal than typical politics coverage. With their subject lines, that means:

• Every email starts with the same emoji.
• They keep their format consistent. They always start with the name of the newsletter and then the subject line.
• The preheader text teases a second story or reinforces the subject line.

Here’s Southwest Airlines, one of the biggest airlines in the U.S. They use humor in their TV ads and in many of their marketing campaigns, but when it comes to email, they’re focused on being as direct as possible. They know their audience is looking for a deal on a flight, and they get right to the point with their emails:

• Their subject lines are focused on the action to take — here’s today’s deal or offer.
• For certain offers, like the credit card pitch, they’ll use the preheader to tease a secondary benefit of the offer.

And here’s Please Advise, a newsletter by Top Hat, a Pittsburgh-based branding and marketing agency. Their brand is fun and creative, and it shows in their subject line strategy. As I look through their newsletter, I see a few great tactics:

• They’ll use puns or emojis to stand out in the inbox.
• They always tease a second story, which gives readers another reason to check out the email.
• The subject lines tease what’s inside but doesn’t give away the full story, which inspires a reader to click.

Testing subject lines with an run an A/B test

An A/B test is a way to test out different versions of your content on an audience. You send one version of your content to a portion of your audience, and the rest gets another. For subject lines, this would mean that you write two versions of the subject line for the same email. Some of your subscribers would receive version A and others would get version B. Ideally, running this type of test can give you an indication of what kinds of subject lines work best for your audience.

Nearly every ESP gives you the chance to test out subject lines. But before you do, keep a few things in mind:

1.) Your results may be skewed if your audience is too small — As a general rule, I don’t encourage clients to worry about A/B testing until they have at least 5,000 subscribers on their list. Any smaller and the results don’t mean much. Can you test with an audience smaller than that? Sure! But expect to run your test for a while — perhaps even a few weeks — before you can feel confident in your results.

2.) Test only one thing at a time — Let’s say you’re testing out your preheader text, and trying to answer a big question: Should we give readers more context about the subject line, or tease a second story? If you do that, the only thing you should change is that preheader text. Keep the subject line constant in both versions. If you’ve got an “A” version of the email with one subject line and preheader combination, and a “B” version with a different subject line and preheader, you won’t be able to tell what really made a difference.

3.) Make sure you understand what you’re measuring before you start the test — Are you looking to see which type of subject line leads to the highest open rate? The highest click rate? The most revenue from a specific email? Before you send, decide with your team what you’re actually trying to measure.

And one more thing: If you’re running an A/B test around open rates, remember that Apple’s Mail Privacy Protection update may impact your results. You may need to run a test several times before you can feel some level of confidence in the results.

4.) Focus on testing the emails that have the most impact — When I start working with a newsroom, they often want to test the subject lines on their daily newsletter. Instead, I’ll urge them to focus on the emails that are designed to sell a subscription, membership, or donation. Why? A subject line test on a daily newsletter might lead to a slight uptick in clicks that day, but one tied to a sale or offer could lead to significant revenue for the organization. Test the stuff that makes you money — then focus on the rest.

5.) Remember: Not all tests lead to change — Often, you’ll run an A/B test and discover that both versions did equally well. That can be frustrating, but it’s a common result. Sometimes, you’ll test a subject line and it’ll make a huge difference. Sometimes, it doesn’t change anything at all. That’s why you test — until you try an idea out, you’ll never know how your audience will react.

What kinds of stuff might make sense for a subject line test? I always like to start with a question that I don’t know the answer to, and then work from there:

• Would readers respond better to subject lines that are shorter or longer?
• Does it make a difference if the subject line is a bit vague, or does it really need to explain what’s happening in the email?
• Should I include the name of my newsletter at the start of the subject line?
• Are readers more likely to open a newsletter if I use the same emoji in every subject line?

Come up with your own questions, and then run a test to see how readers react. Feel free to use other brands or competitors for inspiration for potential tests, but remember: Don’t be so quick to assume that whatever your competition is doing must be a best practice. Whatever you see someone else trying, assume there’s a better-than-average chance that it won’t work for you. Test it out and see if it’s something that makes a difference for your email strategy.

Here’s a calculator to help you with subject line lengths

Some people like to write short subject lines, and some like to go long. (Again: test things out and see what works for you!) But keep this in mind: If your subject line goes too long, it will get cut off in many email clients. 

Now, here’s where things get really confusing:

• Every email client has a different cut-off point. On the Gmail app, you’ll only get about 45 characters, but on the desktop version of Gmail, you’ll get up to 85 characters. In general, I try to stick to about 45 characters for a subject line, and then another 100 characters for the preheader. It’s not perfect, but it works well for most email clients.
• That being said, it’s OK if you go longer than that! I’ve worked with teams that have A/B tested subject lines much longer than 45 characters — sometimes, well beyond 200 characters! — and seen great results. Again: You won’t know until you try.

That being said, I’ve built an A/B testing calculator to help you see how long your subject line and preheader text is. I built it in Google Sheets so you can make your own copy.

Here’s how it works: Open up the calculator. Go to File—>Make a copy, and save the calculator to your Google Drive. From there, you’ll be able to test it out on your own. Enter your subject line and preheader into the proper boxes, and the calculator will tell you how many characters you’ve written. 

It’s not the fanciest tool, but I always use it to check my subject line/preheader lengths before I send an email. I hope it’s helpful for you, too.

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