I’m going to share my personal example here but I’m sure, it will seem familiar to most of you. My inbox is always cluttered with different newsletters I never open, especially designed offers for me, vouchers and coupons that I don’t need and so on. Generally, 99% of messages go directly to either Trash, or the Spam folder because they mostly come from entities which I have nothing in common with, and which want to make money on me.

To put it simplier - I am not sure what makes me more annoyed, the number of emails reaching my inbox or their obnoxious subject lines, which forces me to pack my things and travel to a deserted island somewhere near Hawaii where Internet doesn’t exist.

However, I need to admit that 2016 has been more about spreading valuable and informative content in emails rather than promotional messages for driving traffic. The attitude of digital marketers has changed and no words can describe how thankful I am for that because subscribers are more prone to opening an email if something attracts their attention (their trust improved). It basically comes down to creating such a subject line that makes subscriber encouraged to open the email and keep on reading.

As a Content Marketer, I’ve managed to analyze an outrageous number of subject lines and their effectiveness. It seems that the best ones are usually short, descriptive and evoke curiosity. But, I noticed recurring mistakes that make my eyes bleed whenever I see them over and over again.

To help you maximize your user engagement, we gathered the data and found the list of dos and don’ts of subject lines. Check it out and try some of them next time you plan a marketing campaign.

DOs of Email Subject Lines:

1. Direct and evoking curiosity

Why should anybody want to open something that is not directed to one particular person specifically? Nobody wants to be treated as “one among others”. Making your subject line direct means that you go down to business straightaway. It can’t be too pushy so it should include an element that evokes a sort of curiosity - a slight ambiguity that demands the recipient to keep reading to find out more.

“Seriously, watch this movie”

Here, the subject line somehow makes a recipient feel that he/she needs to open this email to keep up with the newest trends. It’s direct but at the same time, to learn more about what to watch - one needs to look inside the message.

2. Urgency and scarcity

Undoubtedly, one of the most powerful kinds of subject line you have to engage your subscribers. Showing urgency and scarcity makes a recipient think that something may not be at his/her disposal anymore. As human beings, it evokes a kind of anxiety of losing a chance that hasn’t been taken.

“You are out!”

Here, the subject line highlights that if an action isn’t taken, then a subscriber may not have a chance to use their service or its functions. However, one needs to be careful with using such subject lines because if the content doesn’t go together with it, then a subscriber will feel mocked - and it’s never good for your credibility!

3. Limited availability

As written in the above examples, we hate when something is being taken away from us. Something becomes valuable just because it’s temporarily available - the chance of losing it makes it worth our time.

“Taste it before it’s gone…”

Here, we can see two interesting things: using the verb “taste” goes directly to our senses and we try to imagine the sensation; its limited availability makes recipients want to read more to check when it’s possible to try it.

4. Fear of missing out (FOMO)

The idea of not being included in an activity or something that involves other people, creates a sort of fear that we’re missing out something. In 2013 the term of FOMO was added to The Oxford Dictionary due to the popularity of social media which created a need to keep up with whatever is posted.

As we read in Forbes:

Recent studies have shown that FOMO is often linked to feelings of disconnection and dissatisfaction, and that social media fuels it. Think how many people constantly scan email or Facebook to keep up with friends’ updates. Some people don’t just want to keep up – they start to compare and evaluate their lives based on how they see others portraying their own.

However scary it may seem, as a marketer, you can use it to your own advantage when it comes to coming up with subject line ideas because recipients will feel an inner need to find out more “not to be excluded”.

“Don’t Miss The Action This Season”

Let’s take a look on the above example - it makes a recipient feel that there is “the action” that he/she has no idea about and to learn (and keep up with the trends) one needs to open the message. Referring to “missing out” is a powerful leverage, use it wisely!

5. Self-interest and a story

Whenever you explain something, it’s always a good idea to use a story from our own experience to back it up. On top of that, a story evokes curiosity, it also gives credibility to our words. A subject line that suggests that there is a story with precise tips inside the mail, makes the chance of opening greater than you think!

“How Anton Krupicka got 60,000 YouTube views in 7 days”

Here, it’s a clear indication that a recipient can expect a real story that led to the final outcome. Anton Krupicka, an ultra-marathoner, is a real person and based on that, recipients trust such a subject line more than as if it was an anonymous one. They want to find out more about how he managed to get so many views. It triggers curiosity.

6. Encouraging and … (relatively) short

Ok, I will be honest with you here. There is a “universal” truth that subject lines should be short and full of information that pushes a recipient to open an email. It’s been proved that they should be up to 50 characters.

“The 3-step Content Marketing plan”

“Check Our 3-Step Content Marketing Plan That Will Blow Your Mind”

What do you think - which subject line would be more effective? Number one or two?

According to the above, the first one would be better, right? But ask yourself, is there anything encouraging that makes you want to open the message?

The second message is way more descriptive, pushing a recipient to look deeper. The phrase “blow your mind” aims at evoking excitement and it surely does! I would personally shorten it to “The 3-Step Content Marketing Plan That Will Blow Your Mind”. Getting rid of unnecessary “check our” allows us to get straight to the point.

7. Round numbers and credibility

Recently, I read a very informative post on the art of subject line by Sandra Manzanares, where she points out the most important characteristics of a successful subject line. What really made me interested was that using numbers can significantly increase the open rate because people tend to put more trust in it when it’s backed up with concrete facts.

On top of that, Manzaneres highlights to try to use numbers whenever possible, focusing around small odd and even numbers, or large round even numbers. In other words, it’s better to use the number 5,000 instead of 4,998 (even though it’s correct!).

The reason behind it lies within our way of perceiving odd numbers in subject lines as a sales offer - and here, we don’t want to buy anything or being offered. That’s why, while delivering valuable contents to recipients, it’s better to refrain from including odd numbers cause it can cause a reverse effect.

“5,000 people can’t be wrong”

In the example, a recipient’s attention is attracted thanks to two things: round numbers and credibility. The latter one is closely connected with a sort of testimonial - if 5,000 people have made a certain decision and here’s a proof there are right, they must be right!

8. Personalization

Personalization is one of the most powerful tools to attract people attention. It doesn’t matter whether we’re talking about a subject line, content of a welcome email or a phone call - nobody likes receiving messages that are directed collectively to many people. What’s more, no one thinks that getting help from a machine is nice either.

Retention Science showed a 2.6% email open rate increase when names were used versus when they were not. That’s why, gathering the needed data and using it in delivering personalized messages is the key to success in marketing. Thanks to tools that enable to automatize the process of sending marketing campaigns by including the information about recipients specifically, generating and nurturing leads has become easier and more effective.

“Queen Elizabeth: Marta, will you visit me in London?”

Here, I don’t want to show off but The Queen sent me an email. Yes, just for me - there’s my name and the invitation to visit The Queen in London! - Yeah, or it’s what I might think if I didn’t know what’s the reason behind it …

As you can see, using the data you already have about your recipients and incorporate it into subject lines will improve your open rate drastically. To give you an example, you can use their first name or location - it will make the message to seem more important because of its relevance.

9. Call to action!

Hubspot calls it “action-oriented” feature that a subject line should have. It needs to speak directly to a recipient in a manner that makes him/her open the email. So, it’s advised to use a combination of verbs that are “active” (imagine, go, download, do, learn) with particular keywords recognized by your recipients. As we read: Branded keywords are good to use in the emails “from” name and can be used in the subject line as well.

“Marta, learn more about us and win $100!”

Here, it’s a combination of personalization (my name) with a call to action with the word “learn”. What’s more, there is a certain condition - if I “learn” more about a given topic, I will be able to win something, which encourages me as a recipient to find out more about it.

But, you can have the best intentions and think that you’ve read all about subject lines. However, are you sure you’re not making one of these mistakes that make your efforts worthless?

DON’Ts of email subject lines:

Don’t lie

The worst of the top worst subject lines are the ones that attract recipients attention by simply offering something that will not happen. Everyone likes getting stuff for free but screamers like “free” or “free only for you today” when it’s obvious that it’s a pure mockery, will make recipients not only ignore such emails but also label the sender as SPAM.

“We Will Give You The Car For Free!”

There is no doubt that people prefer hearing the truth - that’s why, if you can’t give what you’re offering in the subject line, don’t do it because otherwise, you will lose credibility.

The same goes with being deceiving like “Get a 70% discount on our newest collection … just kidding!”. Not only would you lose any credibility but you would probably discourage recipients to your brand besides receiving emails from you.

2. Caps screamers and “wacky caps”

Please, stop screaming at me! Nobody will persuade me that even the best possible offer is attractive when somebody screams it at your face. This is exactly how your recipients feel when they see a capitalized subject line. It’s a common practise that we find capitalized words but whole sentences is way too much.

Have you ever heard about “wacky caps”? Yes, that the stylistic no-no, where every other letter or a random letter is capitalized in a single word, for example “GeT tHiS OfFeR …” - my eyes are bleeding and I definitely don’t want to learn more about “this offer” because it looks childish and there is nothing special about it.


In this example, it isn’t a bad subject line. It shows a limited availability of this offer which would attract more attention. But, the way it’s written successfully makes recipients a loud “no” to being shouted at.

3. Be rip-roaring, not boring!

The end of story.

Subject lines that limit themselves to short “weekly”, “monthly” updates and keep coming, will be most probably directed to SPAM or simply ignored by a recipient whose excitement about the newest newsletter has nothing to do with feelings more than boredom.

“Our Weekly Newsletter”

As you can see here, there is no personalization, no interest trigger whatsoever. Why should a recipient open it? Indeed, it’s a very good idea to actually segment your recipients so that you can allow yourself not only to be creative but also deliver personalized contents:

“Your readers get a ton of email. They’re much more likely to open your message if you give them a compelling benefit they’ll get from reading it. Don’t focus on yourself. Focus on your reader. Why will they care about what you have in your email? Tell them clearly in the subject line and those that are interested will read on.”

To find out more about subject lines for non-profit newsletters, click here.

4. The Symbol Freak

It’s said that a symbol in a subject line not only says a lot but it also attracts your recipients eyeballs. Symbols are a great way to incorporate something unique into the first thing that your potential/current customers see when receiving a message from you. So, why shouldn’t you be the symbol freak?

If there are too many of them - they don’t engage recipients but make them think that what’s inside a mail is irrelevant.

I was digging deeper into the issue and I found the research published by John Grimshaw where he analyzes the results of their A/B test in terms of a subject line. Version A had a symbol whereas Version B - didn’t. The conversion rate was higher if there was a symbol was included in the subject line:

5. Stop the punctuation abuse

I found this article very informative in terms of what to avoid while creating a subject line and it’s also highlighted that the abuse of punctuation is never a good idea. It’s very similar to the use of symbols - if it’s used properly, it’s going to influence the open rate to grow.

To prove that, as we read here, if punctuation is used in moderation, it can significantly improve your open rate: If you use stops sparingly in your subject lines (2% to 4% of your subject lines), then they take your subscribers by surprise ("Oh my god, a stop!"). Thus, they’re more likely to pay due attention. This translates to a boost of 10% to 20% in open rates.


But, as seen in the example, as a recipient, I would be really discouraged to open the message if a subject line “screams at me” in the full sense - all the letters are capitalized and on top of that, the number of exclamation marks is just overwhelming.

The bottom line

These were our dos and don’ts of email subject lines. I shared with you the practises that can significantly improve your open rate and the mistakes - so that you avoid making them in the future.

I’m sure you realized that there is no universal truth about what kind of subject lines will create your winning strategy. Something that works for one target group will not work for the other one. To check what kind of subject lines (in terms of form and content) work for your subscribers, the best solution is to simply … test your ideas. Experiment by running A/B tests to check the effectiveness of your subject lines.

How about you? Which subject lines do you find the most appealing? Which ones make you annoyed?

Share your opinion with us in the comments!

Marta Debska Customer Success Manager

Posted on September 15th, 2016