Email Subject Lines

7 Types of Email Subject Lines And Examples To Increase Your Open Rates in 2021

Gone are the days when it’s okay to write a generic email subject line to send to people.

Company Weekly Newsletter…

July 2021 Updates…

This month’s promotions…

B-O-R-I-N-G.  Boring!

Not only will these subject lines elicit a snooze fest, but they will also most definitely thrash your open rates.

If you’re new to email marketing…

Or if you’re looking to increase the number of people opening and reading your emails,

I’m going to give you a cheat sheet on how to formulate email subject lines that work.

But before we get started, let me give you a disclaimer.

There are hundreds, even thousands, of ways you can formulate an email subject line.

The sky’s the limit, to be honest.

No one’s stopping you from writing whatever you want.

However, I don’t think it’s very useful to overwhelm you with 797 ways to write an email subject line!

So, what I did was this:

I rounded up the seven most commonly used formulas that are tried and tested to get your subscribers clicking and opening.

I’m not claiming these are the BEST ways to write up subject lines because for some experts, some of these techniques may even be cringe-worthy


Let’s be real.

They work.

And that’s why I’m gonna give them to you –  right now.

1.    The Freebie Email Subject Line

Let’s start with the obvious.

One of the most used clickbait out there is giving out free stuff.

Free eBooks, free recipes, free discount codes, free shipping, free everything…

Who can say no to freebies?

While many seasoned email marketers adamantly believe that the word FREE is already a SPAM trap, it continues to deliver time and again.

Numerous studies and research over the years concluded that getting something for free is an emotional trigger that excites us and pushes us to act.

Even if the freebie is not that valuable or even if we don’t really need the product, we are still enamored by these free things.

Incredibly, even if the email sounds 99% SPAM, many people would still click on the email because of a freebie.

Here are some examples:

Claim your free gift today

Here’s Your Welcome Gift!

Your 3-month free subscription is waiting for you

Because you’re special, here’s an advanced Christmas Gift only for you

Ultimate Giveaway! Download your free e-book now

2.    The Mystery Email Subject Line

Whenever there is a motor accident on the road, you’ll often find that the traffic is rarely caused by the car crash itself.

Instead, it’s because all the other cars have slowed down to investigate what happened.

This is proof of how innately curious human beings are.

If something is left unanswered, or if there’s a cliffhanger…. (Pause for effect)

We can’t just let it go!

That’s why many email subject lines that use the mystery technique never fail to bring in the clicks.

It doesn’t matter if the subject line sounds like ransomware waiting to happen because believe me, people are going to click just to know what’s in there.

No, don’t get me wrong.

I’m not promoting hacking, or phishing or anything of that sort.

What I’m saying is that if you put a bit of mystery on your subject lines,

you can lure your subscribers to open your emails more.

If you want to use this type of email subject line, check out these examples.

I knew it – this habit is what’s holding you back.

THIS technique will dramatically increase your email open rates

How THIS strategy helped this one-year-old startup become a million-dollar business

You want to avoid these 5 careless mistakes most digital marketers do…

If you have a LinkedIn Business Page, you definitely need this

3.    The Shockingly Unbelievable Email Subject Line

I’m sure you’ve seen this type of subject line in your inbox before.

It’s outrageous…

It’s far-fetched…

It’s almost scandalous!

It’s designed to get your emotional response through the roof!

The main purpose of this subject line is to get a reaction out of you.

By being so strange or weird, it stands out in your inbox.

It drives you to click to satisfy your intrigued brain even if at first look, it makes no sense at all.

Many email marketers brand this type of headline as a clickbait no-no.

I mean, I get that.

It’s because this type of email subject line is abused more often than not.

Many people just put in irrelevant subject lines that do not have anything to do with the content.

But that does not mean you cannot use this type of subject line, ever.

You just need to be more creative and back up your claims with relevant info.

I’ll give you an example.

Let’s say you want to send an email to your subscribers about how they can increase their YouTube following.

The content of your email is about the best practices they should follow.

Instead of just saying:

“YouTube best practices you should follow”

Be a bit more creative in crafting your subject line.

Why not use this:

“Why this cat is more popular than you on YouTube”

That’s a lot more intriguing than the first subject line.

But when you write up the content, make sure you tie it up to the email subject line.

Use a popular cat video channel as a reference and list down the reasons it’s generating YouTube views and followers, linking them to the best practices you want to get across.

It’s like writing a super short story – make sure the title is relevant to what you’re trying to tell.

Here are other examples of these subject lines:

This online marketing trick is better than sex

The 5-minute hack that will solve all your email marketing problems

Eat all you can and still lose weight? Yes, please!

4.    The Time Bomb Email Subject Line

As millennials would claim…

FOMO is real.

If you’ve time-warped to 2021 and have no idea what this means,

FOMO is short for the term “fear of missing out”.

This is the anxiety or apprehension people feel when they are not experiencing something everybody else is doing or having.

And what better way to incite FOMO than to put a time limit on a product?

This is called the Time Bomb email subject line.

This is another emotional pull that makes people open emails.

When you are only given a limited time to purchase something or to take action, chances are, you’re most likely to do it ASAP.

There’s a sense of urgency attached to it so you don’t set it aside and forget about it.

There are two types of urgency:

Real-time urgency and implied urgency

What’s the difference?

Real-time urgency is when there is an offer that exists in a specific period or condition and will cease to exist ever again.

For example, if you are having a Black Friday Sale or a Valentine’s Day offer, they won’t be able to get the same deal on a regular day.

You can also do a countdown or limit the slots available.

When promoting these types of offers, make sure the given limit is actually valid.  

You don’t want to dupe your subscribers by getting them to buy, only for them to find out the next week that you’re running the same offer for everyone else.

That’s a surefire way to lose repeat customers and subscribers.

The second is implied urgency.

You can do this using the words “now”, “right now”, and “sale”

While you’re not really specifying a day, time, or date, it still  gives your subscribers a push to take action right at that minute.

While real-time urgency usually performs better, using implied urgency also works depending on what your message is.

Again, it’s better to use implied urgency than tricking your subscribers that the offer is limited when it’s not.

Check out these examples for time bomb email subject lines:

You have 24 hours to claim this limited offer everybody is talking about

One Day Offer: Unlimited storage for only $9

First 50 guests get VIP access

FLASH SALE: Everything Must Go  

Hurry! Get this amazing deal right now!

5.    The How-To Email Subject Line

One of the most effective ways to get people to notice you whether in real life or online is if you offer a solution to their problems.

In fact, that’s basically the essence of selling anything.

What problem are you trying to solve for them?

This is the reason How-To email subject lines are very popular and at the same time, effective.

If you offer them something of value, you’re more likely to get their attention.

This formula is quite simple:

Think of a common problem your audience typically struggle with then offer a solution that is either





Or convenient.

It has to be easy-to-digest because remember – you’re sending them an email, not a 5,000-word essay.

Just make sure that what you’re trying to solve is relevant to your audience and that it’s really going to help them.

Here are some how-to subject line examples:

How to grow your Instagram followers from zero to hero in 3 months

How to generate thousands of website visitors every single day

How this stay-at-home mom made seven figures in less than a year

6.    The Reminder Email Subject Line

With billions of emails being exchanged every day, it’s quite normal for a person to grow tired of opening emails.

Sometimes, even if an email offer sounds very enticing, life’s distractions happen and you forget about that email in a snap.

Maybe you’re even that person who deletes promo emails without ever reading them!

What can an email marketer do then?

Well, instead of sending the exact same message and risk being thrown to the junk folder, what you can do is to recycle your email smartly.

You can do this by sending an email reminder with a snappy subject line.

This is somehow similar to time bomb emails because they also give a sense of urgency.

However, they primarily serve as a reminder that the receiver may have seen this email before.

This instigates a sense of familiarity instead of annoyance so you’re not being persistent.

Here are examples of how you can formulate your subject lines:

Last Call For Entries: Red Carpet Awards Nominations Are Closing Soon

Deadline Today: Have You Claimed Your Discount Code Yet?

Last Chance To Buy: Denim Sale Ends Today

7.    The Numbers Don’t Lie Email Subject Line

Let’s face it.

There’s a reason most of the examples above appeal to the emotions.

Excitement, curiosity, shock, intrigue, urgency…

It’s because these emotions are what usually drive people to click and open emails.

But not everyone who opens emails is driven by what they feel.

There are also people who are influenced by hard facts.

They don’t just open an email because they’ll get an 88% discount in the next 7 minutes…

they need more proof that what you’re going to tell them is legit.

In these cases, you’ll benefit from using what they will not be able to resist….

Numbers, statistics, percentages…

Adding these in your subject lines is a great way to appeal to their logical sensibilities.

Need examples? Here you go:

97% of email marketers believe in this super simple strategy

500 million people watch videos on this platform every single day

Increase your traffic by 157% by adding this element on your website

The truth about why 86% of people use Google Maps to look up a business

The Wrap-Up

So, to recap…

If you want to increase your email open rates in 2021…

You have to know what works.

You have to appeal to your subscribers in an emotional or logical manner.

The formula that will work will really depend on what type of messages you want to send.

These examples above will give you a jumpstart on how to craft those email subject lines ASAP.

You can even combine these techniques to come up with emails that your subscribers will find simply irresistible. 

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