An email is a chance to send relevant, valuable content to your customers. But if your subject line fails, the rest of your content doesn’t matter.

The most important part of your email is the subject line — and it also happens to be the hardest part to write. There’s very little space and the customer’s decision of whether or not to open your email relies on it.

How do you write a subject line that’s too good to ignore?

ActiveCampaign’s Director of Content Marketing, Benyamin Elias, hosted a webinar on all things subject lines:

This post will cover those webinar topics, including:

  • What’s the “job” of a subject line?
  • Why do people open your emails?
  • 4 email types (+ how they affect subject lines)
  • The 2 biggest email subject line mistakes — and 2 things you should never skip
  • Email subject line examples that work

What’s the “job” of a subject line?

The most important job of a subject line is to make people open your email.

It’s that simple. Writing a subject line, however, is less simple.

A subject line is one single line of copy, usually about 40-50 characters max, and that gets cut even shorter on a mobile view. It’s a short window to say everything you want to say about your email content — which means the pressure’s on.

“It’s easy to overburden yourself,” says Benyamin. “When you’re trying to write a subject line, it’s easy to think, ‘Oh my God, I need people to open this, I need people to click it, I need people to buy it. I have to say all of this important stuff in the subject line and convince them to do all of it at once.”

That mentality is how you end up writing a subject line that doesn’t work.

A subject line’s effectiveness comes down to saying the most attention-grabbing, important part of your message. And sometimes, you barely have to say anything at all.

Laura Belgray, a professional writer and founder of Talking Shrimp, released a list of subject lines, one of which ended up producing a nearly 39% email open rate.

And that word was “Dork.”

You wouldn’t expect someone to tease you through a subject line, would you? Why are they calling you that? You have to find out. *Click*

The job of a subject line isn’t to include every single bit of information about your email content. The job of a subject line is to make people curious enough to open your email.

To do that job, here’s what your subject line needs to do:

  1. Grab attention in the inbox. Make sure your key information is compelling. Your subject line has to stop someone from scrolling past your email. Surprise, curiosity, and even emojis can help do this.
  2. Narrow down who you’re talking to. An email that’s meant for one city or one group of people should only be sent to those people. your subject line should reflect this.
  3. Sell directly. Use this tactic wisely. A hard sell in a subject line isn’t always the right approach but sometimes makes sense, like a reference to a specific product. You can entice someone to purchase with your subject line.
  4. Announce information (even to non-openers). For announcement emails, put the most important information in your subject line, so that people who don’t open your emails still read it. Maybe that person isn’t the right candidate for your offer that day, but they could be in the future, and they might remember that email subject line.

This email subject line calls out a specific audience, Chicago friends, and announces the most important point of the email — it’s the last chance to register for the event.

What can you include in a subject line to make sure it does all of the above? It’s a small space!

To get the job done, your subject line should include at least one of these:

  • The benefit of your offer
  • Your reader’s pain points
  • Emotional words
  • Teaser phrases
  • Phrases like “How to do X,” “X ways to do Y,” or “The complete guide to X”

This email from The Copywriter Club does this well.

[NEW VIDEO] is an example of teaser language.

  • The COVID-19 pandemic is a relatable concept right now, and it’s a pain point of most people who get this email
  • “In the COVID-19 situation, what’s your pandemic theme song?” Asking for a pandemic theme song is a little unexpected, which makes a reader want to lea
  • [NEW VIDEO] is a teaser phrase hinting at what’s inside the email — prompting the reader to open the email to find out

The subject line is your reader’s first impression of your email. Are they going to stop and read what you have to say, or keep scrolling?

Why do people open your emails?

Your subject line is a major reason why someone does or doesn’t open your emails — but it’s not the only reason.

Here are 3 main reasons why people open emails:

  1. They’re expecting your email
  2. They already like your emails
  3. Your subject line promises them something or makes them curious

1. They’re expecting your email.

When is your email list expecting to hear from you?

  • If someone signs up for a lead magnet, they’ll expect — and open — your email delivering the lead magnet content
  • If someone buys something from you, they’ll expect a transactional email like an order confirmation or receipt, which they’ll probably open
  • If your email newsletter hints at an upcoming announcement, you can build excitement so more people open your announcement email

2. They already like your emails

There are some newsletters and email lists that people sign up for just to get access to a resource or special offer. But just as often, people sign up for emails because they genuinely like the content.

If you send consistent, valuable content, your readers will open your emails regularly — and even look forward to your next message.

3. Your subject line promises them something or makes them curious

We’ll cover this more a little later, but if you make someone so curious that they can’t resist learning more, they’ll have no choice but to open your email.

People like having information, and they like getting what they want. If your subject line promises them these things, they’re more likely to open your email.

What else affects your email open rate?
Here are some other factors that affect your email open rate:

  • What email list are you sending to?
  • What’s your deliverability reputation?
  • Who is the email coming from?
  • Where are your recipients in the customer lifecycle?

1. Who you send your emails to matters — a lot

If you send emails to an unengaged email list, no subject line in the world will save your open rate. Sending to the right group by segmenting your email list matters to your open rate. If you send unsegmented emails, your emails open rate will be lower — even with a great subject line.

You can segment your email list with marketing automation. In ActiveCampaign, you can design email workflows to automatically send your campaigns to the right people

Automation recipes (like this one for Contact Last Engaged Date) make it easy to automatically segment your email list.

2. Deliverability has a huge impact on your open rates

The quality of your email list, email content, and email open rates all affect your email deliverability. Low deliverability means that your emails are more likely to go to spam, or even not make it to your recipients at all, which can lower your open rates. The effect goes both ways — the more people who open your more emails, the more likely an inbox provider will be to view your content as legitimate (and not send you to spam).

Most email providers help you manage your deliverability. If your email open rate is low, your deliverability will suffer.

3. The sender name can be a deciding factor for email opens

Do you open emails from someone you don’t know? Probably not (unless that subject line was just too good!). The sender name can be another deciding factor for email opens.

  • Is this email coming from a person or a company blast?
  • Is the sender a person that the recipient recognizes?
  • Does the recipient know why they’re getting this email?

It’s usually best to have an email come from an actual person’s name. People are more likely to open emails from familiar senders.

4. Where are your recipients in the customer lifecycle?

People who are already familiar with your business don’t need the same emails that new contacts do. It’s important to segment your emails based on what stage of the customer lifecycle people are in. An existing customer who gets a “Welcome!” email is probably going to delete it.

Someone who just signed up for your email list or made a first purchase are much more likely to open the welcome or order confirmation emails if you send the right ones at the right time.

4 email types (+ how they affect subject lines)

How does the type of email affect your subject line?

Your email content is based on what you’re trying to promote. Different content falls into different types of emails — and different subject lines.

Here are 4 email types and how they affect your subject line:

  1. Announcement or special offer email
  2. Resource delivery email
  3. Reactive email
  4. Content email (like a newsletter, blog, or blast)

Email type #1: Announcement or special offer

An announcement or special offer email is an email that — you guessed it — makes an announcement or shares a special offer.

This kind of email can include:

  • Event announcements
  • Company updates
  • Discount offers

This is an announcement email from Chicago organization Open Books, announcing their Books on Tap event.

This email clearly states the date and what happens on it – the most important details.

How does the type of email impact the subject line?

  • Make your announcement clear and compelling
  • Include the most important details of your announcement in the subject line

Subject lines in these emails don’t have to be fancy; they need to be clear and compelling. As legendary copywriter David Ogilvy says…

“Tell the truth, but make the truth fascinating.”

Email type #2: Resource delivery email

A resource delivery email delivers gated content to someone who signed up for your email list or filled out your lead magnet form. A resource delivery email subject line should tell people exactly what to expect and what they need to do to access the content.

This email holds the key to great gated content.

How does this type of email impact the subject line?

“The story’s about to start (but you must confirm your subscription first).” Cora Stories tells you what to expect (you’re about to get your story), and what you have to do first (confirm your email to get newsletter)

“What I am doing here is taking the reader by the hand and leading him exactly where I want him to go.” – Gary Halbert, direct response marketer

Email type #3: Reactive email

A reactive email is an email that forces some type of action out of the recipient.

Here’s how reactive emails work:

  • Someone takes an action that makes them more invested in what happens next
  • The subject line of your follow-up email prompts them to (re)act

And remember – it doesn’t have to be a clever, punny subject line, just as long as it’s clear.

Abandoned cart emails, like this one from ThredUp, are a good example of reactive emails.

How does this type of email impact the subject line?

The subject line is clear about what happened (the shopper abandoned their cart) and what they need to do needs to happen next (rescue your cart and finish your transaction).

Email type #4: Content email

A content email is a message that shares information, like:

  • A newsletter
  • Blog or other content
  • Blast updates to all customers

These types of emails are typically less segmented and sent on a regular basis, like the weekly InVision newsletter.

InVision knows their newsletter email list well enough to send them more clever-sounding subject lines.

How does this type of email impact the subject line?

  • A weekly newsletter goes to people who want to receive it regularly, which means puns like InVision uses in the subject lines can work better than they do for other types of emails. It’s a personalized, regular email relationship, which makes more “fun” subject lines work.
  • These types of emails share information that you don’t want people to miss. Surprising or unexpected phrases, like “a good pizza advice” can catch the eye and encourage opens

The 2 biggest subject line mistakes – and the 2 things that you definitely can’t skip

No subject line is perfect. But to maximize your email opens, here are 2 subject line mistakes to avoid — and 2 elements to include in every subject line.

The 2 biggest subject line mistakes

The 2 biggest subject line mistakes you can make are…

  1. Summarizing content
  2. Making everything a discount

1. Summarizing content

Consider the subject line: “More sales in less time (without sleaze).”

It sounds like a good benefit, right? Who wouldn’t love more sales in less time, and doing it without being a sleaze? The problem is that there’s no reason for a reader to believe that they can get that benefit based solely on the subject line copy.

“There’s no particular reason for me to believe from the subject line that these emails are going to give me this information better than any other source of information,” says Benyamin. “What makes this promise believable? I would be willing to bet that a lot of the rest of this email is fantastic and does, in fact, give the information needed to make more sales more time. But that work isn’t getting done in this subject line.

2. Making everything a discount

Offering too many discounts can make your emails less effective.

If your “Last chance!” emails are always followed by another sale right after, people are less likely to believe you. Your email loses that urgency, that incentive that makes people buy.

Udemy emails do this when selling their online courses.

When are these courses ever NOT on sale?

Benyamin can attest to this: “I don’t think I ever see their courses not on sale for $12.99.”

“A big reason so many businesses compete on price is because they can’t prove what value they offer, so they’re stuck with the one selling point that’s a breeze to communicate: cheapness.” – Mish Slade, founder of The Duff

2 elements to include in every subject line

Here are 2 things you can’t skip when you write subject lines (unless you just don’t like email opens):

  1. Relevance. How does your subject line connect to what your reader wants, or something they’ve done?
  2. Curiosity. How can your subject line tease your email content, without giving everything away?

Relevance is fairly straightforward: Send emails that are relevant to people. The emails people get need to be relevant to what you know about them, including:

  • Age
  • Gender
  • Location
  • Lifecycle stage

And plenty more.

But what’s even more important than being relevant is making people curious.

Behavioral economist and Carnegie Mellon professor George Lowenstein researched and wrote a paper on the psychology of curiosity.

Here are Lowenstein’s 5 ways to make people curious:

  1. Ask questions
  2. Start stories but leave them unfinished
  3. Be unexpected
  4. Imply that you have information that they don’t
  5. Imply that THEY have information that they’ve just forgotten

Adding 2 or 3 of these curiosity levers to your subject line copy gives your email a much better chance of being opened.

This is how it works on an actual line of copy.

Consider this headline: “How to earn half a million dollars a year.”

When you add curiosity levers, your headline goes through a transformation that gives it a hook:

What makes “Do you have the courage to earn half a million dollars a year?” more effective than “How to earn half a million dollars a year”?

The initial version implies that you have information that your reader doesn’t — but that doesn’t mean they believe you.

The final version still implies that you have that information, but that’s not the main focus of the subject line. Instead, asking about courage is unexpected and interesting. It makes people think “I don’t know, do I?” — which makes them open the email.

Real email subject line examples that work

Here are 3 examples of business email subject lines that work.

1. “So you wrote a novel…now what?”

This sounds like a question that someone would actually ask, right? That’s why it’s an effective subject line.

National Novel Writing Month is every November, and a common pain point from people who participate is, “I wrote 50,000 words in 30 days in the month of November. I have a novel. What do I do with it now?”

The copy sounds like something someone actually says when they finish writing.

This subject line uses ingredients are relevance and curiosity:

  1. It says exactly what the reader is thinking
  2. It implies that there’s information in the email that the reader doesn’t have but needs

2. “5 chickens and 2000 rounds of ammo”

That’s not something you hear every day — or see in your inbox, for that matter.

It’s nearly impossible to skip clicking a subject line that says something this surprising.

The content of this subject line is unexpected. It implies that there’s a story there, which makes it stand out against other emails.

This comes from copywriter Abby Woodcock, and it starts with a story: “I almost bought five chickens yesterday.” This subject line uses 2 of the curiosity levers: surprise and leaving a story unfinished.

3. “Your chance to be publicly humiliated – FOR FREE”

If this subject line showed up in your inbox, wouldn’t you have to know more?

“Humiliated for free?? Sign me up! Wait a minute… what does that mean?”

Again, this subject line works because it’s unexpected. With so little space, unexpectedness is one of the most powerful curiosity levers for subject lines.

This subject line achieves unexpectedness through contrast. Humiliation is generally thought to be bad, but copy saying it’s “your chance” and free makes it sound like a good thing.

Contrast makes your subject lines more unexpected. This subject line copy also challenges a common belief — the belief that public humiliation is bad.

Copy can be powerful. And your subject lines can be, too, when you know how to write ones that get your emails opened.

BONUS: Short on time, or need some help coming up with great subject lines? Let us give you some subject line ideas with our free subject line generator!