How to write email marketing subject lines that get opened

Email marketing subject lines can seem intimidating when you’re staring at a blank field.

The truth is, a lot goes into a really effective subject line. That said, once you get the hang of writing them, subject lines will be your secret weapon for sky-high open rates.

As somewhat of an email marketing expert (I’ve helped companies send thousands of marketing emails over the past five years, so I know what works), I’ll walk you through:

• The building blocks of a solid email marketing subject line,
• some examples,
• and a few tips for getting AI to write them for you.

What is an email marketing subject line?

An email marketing subject line is the text that shows up alongside a new email notification in the recipient’s inbox.

The subject line is your first contact with your email subscribers. That makes it a great opportunity to tell them why they should open the email at all.

Why do email marketing subject lines matter?

The big question is, why are we even addressing email marketing subject lines here? Well, they do a few very important things.

• They set expectations off the bat. Subject lines give your subscribers an idea of what’s contained in the email.
• They generate interest. With creative wording or exciting text, a subject line can get the recipient excited to open your email.
• They make your emails a priority. If you give your subject line a sense of urgency, it can motivate them to click immediately before they lose interest.
• They ensure that your emails get opened. This is one of two things that really matters — the other is deliverability.

What makes a great email marketing subject line?

So, subject lines are important. How, then, do you write an exceptional one? You should include:

• Specific language. “Major deals on fall clothing” tells the recipient more about what they’re getting in the email than “SALE!!!”
• Exciting wording. On the same note, “Limited-time coupon inside” will pique interest better than “Announcement about current inventory.”
• Clear value. Don’t expect a subscriber to open your email if they can’t tell what’s in it for them, so mention the good stuff inside.
• A call to action. This one is optional, but if you need your subscribers to take a specific action after reading your email, tell them so right away in the subject line.

📖 Read next: How to build an email list

Email marketing subject line examples from real brands

Now that you’ve got a clearer idea of what goes into a good subject line, here are a few examples you can steal if you’re still looking for inspiration.

Follow-ups

Your appointment is confirmed, [name]!

We had a blast talking to you today!

What’s on your mind, [name]?

Introductory emails

You’ve unlocked a world of deals at [brand name] 👀

An exclusive welcome to the [brand name] family

Come on in and have a look around, [name]!

Promotional emails

Don’t head out the door without this [product type]…

For your eyes only: brand-new [product type]

Introducing our new [name of service]

Re-engagement emails

Long time no see, [name]!

Let’s catch up…

We’ve got a gift for you, [name]!

Customer service emails

[Inquiry topic]: We’re here to help.

Let’s get your [topic] questions answered.

We got your message about [topic]!

Newsletters

P.S. Get our best email newsletter examples here.

It’s PSL season 🍂 at [company name]

Webinars, features, and guest blogs, oh my!

A look back at [month]

Informative emails

Take your [topic] skills to the next level in 10 minutes.

Read this before your next [type of product] buy…

The [topic/industry] world is changing fast (and we know why)

Playful emails

Sent from the couch: [topic]

Drool-worthy deals on [product type] 😍

Brb, obsessing over [product type, topic, etc.

Email marketing subject line character count

Now that you have a few examples of AI prompts to help you get started, let’s talk about some of the specifics so you can write your own prompts and subject lines.

What should your character count be?

The research tends to show that email marketing subject lines should be between 30 and 60 characters.

You’ll notice in some of the screenshot examples throughout this article that many subject lines are cut off on mobile devices. I specifically took screenshots on my phone to show this to you. If you can write a subject line that gets your point across in fewer characters, that’s what I suggest doing.

As far as words go, 9-word subject lines work best. Again, the fewer the words the better.

How to write catchy email subject lines using AI

AI prompts for email marketing subject lines

The key to a great AI email marketing subject line is the right prompt(s). Here are a few of our favorites. Just open chatGPT and copy/paste these in:

• Write 25 email marketing subject lines for a promotional email advertising a sale. The theme is [subject]. The deal is [offer]. The character count should be 60 or fewer. Use emojis.
• Create 25 email marketing subject lines for a [topic] email newsletter. The character count should be 60 or fewer. Use emojis.
• Write 25 email marketing subject lines that create a sense of urgency for a product. The character count should be 60 or fewer. Use emojis.

Which keywords should you use? 

You’ll also want to be specific with any AI engine about the subject matter of your emails, so it helps to use keywords in your prompts like:

• Product launch announcement
• Webinar/event invitation
• Flash sale promotion
• Abandoned cart reminder
• Monthly newsletter

You may also want to give your AI tool an idea of the end goal of the subject line, so consider adding:

• Create a sense of urgency
• Encourage recipients to buy/register
• Explains the product
• Teases a new launch
• Thanks them for their business

Recipe for the perfect email marketing subject line

Now, I know that was a lot of information at once, so here’s a quick and easy recipe you can use to either guide your favorite AI tool or write your own subject line.

1. Know what you want readers to do after reading the email and use descriptive or motivating words in your subject line (like “learn,” “open,” “find out,” or “take advantage of”).
2. Reference the subject matter of the email in your subject line.
3. Make sure your subject line fits within 60 characters and 9 words.

Email marketing subject line best practices

You’re almost ready to start sending. Before you do, keep a few key points in mind.

• Be creative. If you wouldn’t open it, don’t write it. Have fun with alliteration, emojis, or puns alongside your core message.
• Choose your words carefully. Be sure to avoid all-caps words like “FREE,” “WINNER,” OR “ALERT.” These can come off as spammy.
• Ask questions. This is a classic engagement technique. A question gets your subscribers thinking and encourages them to get invested in the email.
• Use FOMO. We all suffer from it, so let recipients know that they’ll be missing out if they pass over your message.
• Speak in the second person. Talk directly to your audience with “you” and “your” verbiage to make it feel more personal.
• Don’t bury the lede. Front-load the most important information at the beginning of your email subject line.
• Personalize your subject lines. The data shows that personalized subject lines can boost open rates by nearly 30%. Feel free to include recipient names or other details they’ve shared with you.