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The 17 Best Email Subject Lines for Increasing Open Rates [+ Video]

Discover the carefully guarded source of the world’s most effective email subject lines that most professional copywriters don’t like to share


What’s the source? Well, it’s no big mystery. It’s simply that all editors and copywriters are veteran thieves. They all study, admire, and copy each other’s work. They find formulas they love, and they emulate them in the future. Maybe that’s why they call it copywriting [1].

The average internet user is bombarded with dozens if not hundreds of email subject lines every day. Most of us have developed an anti-headline defense and tune out when we sense an email subject line is trying to sell us something.

For both news articles and advertising, 75 percent of your success is gated by your headline. If the headline does not convince the user to read on, all is lost.

One of my favorite tools to play around with is MailChimp [3]’s subject line suggester which allows you to put in the key words of your subject line and will return the syntax of those words that have performed best in the past for other email campaigns. It’s only available if you have a MailChimp account, but you can get a free account on their website, so you might as well give it a test. I’ve used this tool to to help come up with even better versions of each subject line below.

We’ve also released our Email Subject Line Smackdown video at the bottom of this post.

1. REASON WHY Email Subject Lines

The Reason Why email subject line convinces the user “why” they should do something based on a number of “reasons”. People respond well to lists, as you’ll find out later, and according to the results below, they respond well to reason too.

Winner: “Reasons Why” (as in “5 Reasons Why You Should Use the Reason Why Subject Line Template“)

best email subject lines

2.  BENEFIT Email Subject Lines

Professional copywriters [4] know to emphasize benefits over features. The benefits of my losing weight are enormous. My clothes will fit better. My feet won’t hurt as much. I love the benefits of losing weight. However, one of the features of losing weight is something my doctor calls a “diet.” I have a lot less enthusiasm for this feature than I do the benefits.

Examples of the benefit subject line are everywhere. They generally contain an implied promise.

An example of one subject line for a client, “20 Country Slow Cooker Recipes,” when turned into a benefit subject line, “Top 10 Lazy Skillet Meals” zoomed from an 18.2% to 19.6% open rate. Here are more examples:

3. QUESTION Email Subject Lines

The linguistic structure of a question requires the reader to pause and respond. Question subject lines generally pull well because they’re short and entice the reader to find out the answer. In many cases, the reader already thinks they know the answer, and your headline is merely feeding their need for affirmation.

According to Brian Clark of Copyblogger, starting a headline with the question of “Who Else Wants…” is “a classic social proof [5] strategy that implies an already existing consensus desire.”

Winner: “do you think” (as in, “Do You Think You Can Retire at 65? Think Again!“)

best email subject lines

4. TESTIMONIAL Email Subject Lines

Testimonials help convince buyers because they provide validation and social proof. While testimonials usually appear in the body copy of a sales letter, they can also be effective in the subject line.

Note: While “all caps” normally increases email open rates versus “standard upper and lower,” our testing reveals that the standard capitalization used above often wins when subject lines include names and other proper nouns.

5. HOW-TO Email Subject Lines

The how-to subject line is more specific because it promises to reveal “how-to” achieve the benefit. It’d hard to write a bad how-to email subject line. Simply join a mouthwatering benefit to the words “how to.”

Winner: “how to make” (as in, “How to Make a Fortune with a Foolish Idea“)

best email subject lines

6. NEWS Email Subject Lines

If your email offers something new, something your customer can’t get elsewhere, consider the news subject line.

7. FASCINATION Email Subject Lines

Fascinations are compelling, benefit-driven bullet points that motivate the reader to discover the answer. Fascinations exploit the reader’s curiosity. Often, fascinations include the words “discover,” “secrets,” and “amazing.”

Winner: “Discover the” (as in, “Discover the Ultimate Options Trading System“)

Surprisingly, farther down the list in the one-star section was “Top 10 Secrets” with just one star. Guess everyone’s over all those so-called “secrets”.

best email subject lines

8. TARGETED Email Subject Lines

This subject line is very direct in that it specifically identifies its intended audience. 25-year copywriting veteran Mark Johnson told us that this is his favorite type of subject line. “The reason is because targeted subject lines are about the reader; and more than any other topic, people want to read about themselves,” says Johnson.

9. HYBRID and PERSONALIZED Email Subject Lines

All the email subject line archetypes can be used in combinations, and many can be personalized. Johnson also noted that incorporating numerous archetypes into a hybrid form is usually a preferable option to copywriters. For example, using a Targeted email subject line in conjunction with an Urgency email subject line, or a Reason Why subject line used in conjunction with a Fascination subject line.

10. LIST Email Subject Lines

Readers love lists because lists comprise convenient summaries. Note that the blog you are currently reading is a list. One of the easiest ways to get double duty from your subject lines is to start with a great idea based on one of the proven archetypes and combine it with the List subject line.

Winner: “Strategies for” (as in “10 Win-Win Strategies for Quitting Your Job”)

best email subject lines

11. INTRIGUING PROMISE Email Subject Lines

Anyone with a curiosity quotient higher than room temperature can be intrigued and motivated to open an email.

But using the intriguing promise subject line absolutely requires that you fulfill the reader’s expectations with information that at least partially satisfies his curiosity. The product you are offering must completely fulfill the promise.

This one is hard to rate as well, so here are a few intriguing promise subject line templates:

12. TEASER Email Subject Lines

A teaser subject line is also intriguing, but without an implied promise beyond an engaging narrative. Teaser subject lines must be followed by an expertly crafted story that instructs or entertains, otherwise the reader will feel deceived.

13. SEASONAL Email Subject Lines

The Seasonal email subject line references a holiday or time of year and as you can see, performs well. Often your control mailing can be adapted to use a seasonal reference, thereby increasing response.

It’s hard to pull a winner, but when the word “holiday” was added to the list of holidays I tested, it came up on top. “A Christmas” and “this Christmas” came up on top with five stars too, before I added “holiday.” Clearly, people don’t need specifics to open the email.

best email subject lines

A good variety of holiday subject lines:

14. KEYWORD Email Subject Lines

Conventional search engine optimization wisdom says keywords are the most important aspect of a blog post title. If the blog post title doubles as an email subject line, then keywords are important.

But the blog post title and the email subject line don’t necessarily need to be identical. The blog post title can be the topic headline of the email content after it is opened.

The email subject line can be some other combination of words that prompts the recipient to open the message. This strategy provides greater flexibility in writing email subject lines.

Nevertheless, keywords are keywords. We use them generously in subject lines, headlines and editorial copy because we know that customers search them and respond to editorial content that contains them. So using keywords in an email subject line is encouraged but not mandatory.

15. ISSUE-BASED Email Subject Lines

The Issue-based email subject line simply announces the editorial content contained in the body copy. It tells what’s inside, and subliminally sells what’s inside.

Winner: “Daily Scoop” (as in, “Mequoda Daily Scoop: Digital Enlightenment“).

best email subject lines

16. COMMAND Email Subject Lines

The Command email subject line directly tells the reader what to do. It always begins with a verb that demands action.

17. URGENCY Email Subject Lines

Using urgency in the subject line is a time-honored method of creating anxiety. Some people respond better to the threat of losing than to the promise of gaining, however it’s not the best performing subject line in this list. When used creatively and mixed as a hybrid with some of the others, it can work quite well.

Winner: “last chance” and “today only” variations (as in, “Last Chance to Send Your $10” and “Save 50 Percent Today Only“).

best email subject lines

So let’s just keep in mind that the results we’re seeing are based off of the subject lines sent by their customers. With that said, MailChimp delivers over 700 million emails per month for more than 500,000 customers. So what you’re seeing is a pretty good representation of what to do – and what not to do.

All great journalists and copywriters maintain an extensive “swipe” file to inspire them and help break a logjam of so-called “writer’s block.” You should, too.

Every time you read an email subject line or news headline or magazine cover line or advertising headline that strikes a responsive chord, copy it into an every-growing document entitled, “Headlines I hope to use someday.”

You should also read about how to mix and match these email subject lines to make them multitask [6].

Email Subject Line SmackDown

Mark Everett Johnson [7], a panelist on our Email Subject Line Smackdown webinar, has been a copywriter for years. In fact, his career spans over 25 years as a communications specialist and freelance writer.

Below you will find four rules Mark uses while creating email subject lines. He first memorized these concepts 25 years ago for how to write a better headline.

Mark’s four email subject line copywriting tips:

1.    Offer a quick and easy way to do something.
2.    Talk about the reader’s self-interest – something that is a benefit.
3.    Give the reader some news – especially good news.
4.    Arouse curiosity, preferably related to points 1, 2, or 3 above.

To see these tips in action, Mark joins two more of our favorite copywriters, Peter Fogel and Peter A. Schaible, analyzing different subject lines in our Email Subject Line Smackdown webinar, now available to watch for free:

This article was originally published in 2009 and is updated frequently.