How to write email subject lines that get opened

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For some marketers, email subject lines are an afterthought. For others, it comes first. But for most, it’s the single element of any email that they spend the most time agonizing over. 

After all of your hard work writing engaging copy and designing a visually appealing email, you need your recipients to actually open your campaign. If they don’t all that work has been for nothing.  

Fortunately, there are certain things you can and should always consider when crafting compelling email subject lines. 

Here are our 11 essential tips to consider whenever you’re writing your email subject lines. 

1. Know your audience

It feels like it goes without saying, but for any marketing activity to be successful, you need to know your audience. If you don’t know this, then you don’t know how you should be approaching, addressing, and marketing to your audience. 

 Knowing your audience will help you to devise subject lines that will work for you. That really is the first step – knowing who you’re sending the email to and why, is essential in helping you decide where to start with your subject line. 

2. Set clear expectations

Time is precious, so you need to make sure that you’re front-loading your subject lines with the benefits. Make it clear what the recipient gets from opening your email. 

Additionally, being clear with your audience from the beginning strengthens the relationship between you and your customers and prospects. If your subject lines always deliver on their promises when the recipient opens the email, they’ll know to trust you.  

For example, if your email is about the new summer product line that your brand is launching, make sure you put that in the subject line! Trying to be too clever with your subject lines could lead to them tanking. 

The following examples are clear and to the point: 

  • Our new summer range is here, look and shop now 
  • Available now: summer styles 
  • Shop our new summer range today 

If anyone opens these emails, they should know exactly what they’re going to see.  

3. Don’t mislead the reader

Following on from the previous tip, you don’t want to mislead your readers, as that can be damaging to your relationship. 

Don’t promise anything in your subject lines that your email doesn’t deliver on. Not only is this disingenuous, but it’s also spammy. If you take this approach your email campaigns will be winging their way to spam folders in no time at all. 

Either that or your hard-earned subscribers and customers will be searching for that unsubscribe link. 

One misleading tactic that I’m genuinely surprised to still be seeing from brands is the classic ‘RE:’ approach, in order to make you think it’s a reply to an email that you’ve already sent or received before. 

Example of a misleading email subject line

It may get you opens, but it also gets deletes, spam reports, and low click-through rates.  

4. Keep it short and snappy

Nearly 50% of all emails are now opened on mobile devices. This brings another issue for you to deal with when writing engaging subject lines for your email marketing campaigns. Smaller screens mean less space to work with. 

With most mobile email clients, you’ll probably only have around four or five words before your subject line is cut off. 

Therefore, it’s important to make your subject line pop in those first four or five words. If you can make a strong subject line in just four or five words (or less) then do it. 

5. Stand out in the inbox

333 billion emails are sent and received every day around the world. Understandably, with that many emails circling inboxes, it’s increasingly difficult to stand out.  

Having said that, it’s important that you don’t utilize spammy practices. This significantly reduces your chances of even getting your email into the inbox at all. 

Here’s a list of some things that you shouldn’t do when trying to stand out in a crowded inbox: 

  • Don’t use ALL CAPS – this can be considered spammy 
  • Stay away from heavy use of exclamation marks!!!!!!!! 
  • Avoid overzealous use of currency signs ($$$$$ or £££££, for example) 

You don’t want your hard work to be for nothing, so avoid these approaches when crafting your subject lines. 

6. Emojis have their place

Emojis have found their way into almost every aspect of everyday life. Heck, they even made a truly awful movie about them. So, don’t be afraid to give them a whirl in your email marketing campaigns.  

 Back in the day, early emoji adopters certainly stood out in their recipients’ inboxes. But slowly marketers have come to realize that these cheeky little icons can help you catch the reader’s eye.  

So, when used effectively, emojis can help your subject lines stand out. Econsultancy summed up its recent research into emoji usage in subject lines, noting that an emoji ‘makes a good subject line better’, or ‘makes a bad subject line worse’. 

So again, you need to ensure that you’re using emojis in the right way for them to be effective. 

It’s important to consider some pros and cons when using emojis in subject lines.  


  • They can help your subject lines stand out. 
  • They’re more emotive. 
  • You can use them to get a point across without the need for words. 
  • Especially useful for mobile. 
  • When used properly, they can add context to your email subject lines (again, useful for mobile). 


  • Improper use can be detrimental. 
  • Inconsistent rendering across mobile devices, platforms, and email clients (a good resource to check the differences is Emojipedia – The ‘grimacing face’ emoji is a great example of how emojis can look very different cross-platform). 
  • Some audiences won’t like them (which takes us back to the first tip – know your audience). 
  • Irrelevant use can be confusing – is it immediately obvious what the emoji is, and why it’s being used? If the answer to either is no, don’t use it. 
  • Some emojis can have multiple meanings, so make sure you understand any and all meanings before you use them.  

7. Show some personality

Most of the subject lines that lead me to open emails in my inbox are either to the point or have a bit of personality shining through. Adding personality to your subject lines can be a powerful tool in getting recipients to open. 

This tip relies heavily on your brand’s tone of voice. Are you a playful brand? Can you be cheeky? Are you a leading authority in your field? Your tone of voice is your brand personality, so it’s important you have a clear understanding of it before you start writing your subject lines.  

Even better, if your tone of voice allows you to have some fun with your subject lines, then do it. As long as you keep it relevant, it opens up a world of limitless possibilities for your subject lines. 

8. Urgency and scarcity work wonders

If you’re promoting a time-sensitive offer, deal, or sale, then be sure to mention it in the subject line. 

Good use of urgency will have your recipients clicking in no time. Language like ‘buy now’ or similar can subconsciously trigger the desired reaction from the reader. 

Likewise, scarcity can also help to influence the recipient to open your email and then take the desired action. 

Limited time or limited quantity offers are the most commonly used approaches. If you’re not selling a product, you can always consider similar tactics such as a countdown until an event. It all has the same FOMO (fear of missing out) effect.   

9. Ask questions

One of the best ways to get a customer to complete an action is to pique their interest and curiosity. Asking a question in your email subject line is the perfect way to do this. 

If you’re a retailer, it can be as simple as asking whether the recipient wants to see your new collection, or even better, receive a discount on their next order, like this: 

Hi Jenna, do you want 20% off your next order? 

Or if you’re a B2B business, you can ask a question that is relevant to some content that you’ve produced, as we did with our global benchmark report: 

How do your results compare to the competition? 

The reader’s natural curiosity is enough to make them want to click. When they do, it’s up to you to make sure you keep them curious enough to click through the email. 

10. Don’t overcook your personalization

The best way to explain the use of personalization in email subject lines would be ‘less is more’. While the odd usage is okay, repetitive or irrelevant usage can turn recipients off. 

We also have to remember that consumers are far savvier about the email marketing practices of brands than they were in the past. 

Overuse of first name personalization in subject lines especially can make recipients blind to the tactic. 

Still, consumers expect some form of personalization in your email marketing, so it’s important to change it up and try different tactics regularly.  

This leads me to my final tip…  

11. Test, test, test

Perhaps the most important tip of all is to make sure that you’re always testing your subject lines and measuring their performance and impact. 

It’s essential that you continue to tweak your email subject lines in order to get the best possible performance from your campaigns. 

Here’s a handful of things that you should consider when testing your subject lines: 

Don’t get caught up in what you think your recipients expect 

While, to a certain extent, you do have to predict what your recipients want, that doesn’t mean you know what they’re expecting. Keep them on their toes with your campaigns, and they’ll become more inclined to open your emails. 

Don’t be cautious 

Playing it safe is fine if you want to do okay. But most of us want to do better than okay. So that means throwing caution to the wind with your subject lines and stepping out of your comfort zone. It’s okay to brainstorm some really ridiculous subject lines, before scaling them back to something that you are happy with. 

Monitor what works and what doesn’t 

Make sure you’re tracking any tests that you’re doing so that it’s easy to look back and see which type of subject lines worked best. Otherwise, you’ll end up not knowing which types of subject lines work best for certain types of campaigns. 

Don’t stick with a subject line that worked once, or worked well two years ago 

While it may be easy to stick to the old adage of ‘if it ain’t broke, don’t fix it’, this doesn’t really work with email subject lines. While you may want to stick to a certain formula if you’re sending regular, consistent email campaigns, you should also consider that recipients will get used to seeing the same types of subject lines. In time, they could become blind or oblivious to them. 

One approach you can use is to ensure that the first part of your subject line identifies the type of email you’re sending, before specifying the content it contains. 

Let’s say you send a monthly newsletter to your subscribers, but all you do is change the month. So, your subject line looks like this: 

May Newsletter 

It’s not the most inspiring or eye-catching subject line that you can use here, is it? 

This is where emojis can be useful. You can add context to them, and over time your recipients will begin to associate that emoji with a certain campaign. 

Seeing as we’re talking about a newsletter campaign, let’s use the newspaper emoji. 

Then you also add a callout to some specific content that’s included in your newsletter. This will make the subject line different every time, while still being clear about its contents. 

Put these elements together, and you end up with a subject line that looks like this: 

📰 May newsletter: Email subject line guide, cookie update, and new platform features 

Sure, it’s a lot longer, and the full subject line will likely be truncated on some displays, but it’s better. By using an emoji and adding clear information about what the email contains, it’s already more appealing to the recipient.  

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