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Your Guide to Writing the Best Email Subject Line

Skye Schooley
Skye Schooley

Follow these steps to write email subject lines that appeal to your customers.

If you have a small business, you likely have some type of email marketing campaign – but is it successful? Your target audience is inundated with daily emails, and they make instantaneous choices about which ones to read and which ones get deleted.

To increase your chance of not only reaching peoples' inboxes but capturing their attention, it is critical to have carefully crafted subject lines. Follow these steps for creating an engaging email subject line that will appeal to your customers.

Why is a marketing email subject line important?

It doesn't matter how great your marketing emails are if your subscribers never open them. Recent studies show that nearly 80% of emails are deleted immediately. Creating a great email subject line is a key factor in ensuring your emails are the 20% that individuals do open and read.

Your subject line is the first point of dialogue you have with your subscribers, so you want to send a positive message. Your subject line informs your reader and gives them context as to what information you are sending them.

"For some, [email marketing] is the only form of communication they have, so you want to make sure your message is not just received in the inbox but seen," Shannon Hampton, director of email and CRM marketing for Fracture, told "Transactional messages are a great example of this; these are very important communications that you want to make sure your customer sees that usually contain important information."

If your reader only sees a subject line and doesn't open your email, you want to make sure they understand the most important part of your message.

How to write an email subject line

We spoke with marketing experts to learn what goes into writing an effective subject line. To create great subject lines that return the results you are looking for, follow this five-step process. 

1. Write the subject line first.

A subject line makes or breaks your email open rate and overall email campaign, so you musn't leave it as an afterthought. Experts recommend always writing a subject line first.

A subject line is similar to an article title – it guides the content of your email and should convey your topic. By writing your subject line first, you reduce the risk of creating a haphazard subject line, or worse, forgetting to write a subject line altogether.  

2. Decide on the key points your subject line will convey.

To create an effective subject line, what message are you trying to convey? For example, are you sharing a product promotion? Are you sending an abandoned-cart reminder? Or are you requesting an immediate response? These intents all require different key messaging. You want to be clear, specific and to the point.

If your email requires a call-to-action (CTA) or a response by a certain deadline, ensure that your subject line adequately conveys this information. This not only increases your odds of having your email opened, but it also increases the chance of your target audience performing the action you are requesting.

"The key points to keep in mind when writing a subject line are relevancy, a sense of urgency, full transparency and CTA. Ask yourself, what is the expected action that you want your subscribers to take?" said Hampton.

Although creating a sense of urgency can entice readers to open your email, use it sparingly and intentionally.

3. Choose your words carefully.

Once you identify the key message you want to convey, you then need to choose your words carefully. Your tone and words should match your brand and target audience. Create a catchy email subject line that is informative and personalized to each reader. For example, a subject line that contains a subscriber's name can boost open rates by 10% to 14%. However, there are other ways to create a personalized subject line beyond simply using a reader's first name.

"Work on improving your list segmentation so you can get more personal than just names," said Melissa Sargeant, chief marketing officer of Litmus. "For example, if you're trying to sell lawn furniture in cooler months, take subscribers' geography into account, and target the ones in warmer, southern states, not those up north. Along these lines, questions can work well for many audiences, but not every time."

What works for some will not work for all. Consider whom you are speaking to and how your email is relevant to them. Creating a familiar and friendly relationship with your audience goes a long way. 

4. Edit and refine your subject line.

One of the most important elements of a subject line is length. Email inboxes limit the number of characters a reader can view in the preview text, so create short, attention-grabbing subject lines. Just exactly how long should a subject line be? Experts recommend subject line length stay between five and eight words, or roughly 27 to 40 characters (including spaces).

You should also consider what devices your email recipients will primarily be using (i.e., desktop, tablet, mobile), as this will affect how many characters they can view.  

"Different devices have different character limits, but keeping it within that [27 to 40 character] range is a good best practice," said Hampton. "If your subject line runs over that limit, which is bound to happen at some point, make sure you get your main point across before the 40-character mark for those devices that show fewer characters."

5. Test your email subject lines.

When creating new email subject lines, it is always a good idea to test them to learn which ones are most effective for your business. There are multiple ways to test, depending on how much time you have to gain insight. Hampton gave the following two examples of how small businesses can test email marketing subject lines.

20/80 testing, also known as a 10/10/80 split 

  • What to do: Send a control subject line to 10% of your email list and the test subject line to another 10% of your email list (equaling 20% of your mailing list). Test for at least four hours and up to 24 hours to allow enough time to gather sufficient insights. Then send the winning subject line to the remaining 80% of the list.

  • Best for: 20/80 testing is good for businesses that are looking for immediate subject line impact.

50/50 testing

  • What to do: If you have more time, you can test across multiple campaigns, and split the email 50/50. Send the control version to 50% of your mailing list and the test to the other 50% of your mailing list. You never want to test too many email subject lines at one time; instead, you should be progressive, making optimizations and changes along the way as you learn.

  • Best for: Using the 50/50 split test method is particularly good when you want to measure subject line performance at the campaign level versus a single email send. For example, if you have a series that you are doing on a particular topic or a specific message type, like testing sale subject lines, test across all the emails sent for that promotional period.

If you don't have the ability to test subject lines on your email list, send them to trusted friends or colleagues to get their opinions. You can also use email testing tools like Litmus Email Previews, and SpamCheck. It is important that you track which subject lines perform well and which ones receive low open rates so you can identify trends and improve your campaign.

What to avoid in your subject line

One of the most important rules when crafting an email subject line is never to use clickbait or spammy verbiage. It may seem enticing, but you will quickly lose subscribers if your messaging is seen as spam, or if you promise your customers one thing and deliver another. Getting your email opened is important, but your end goal is to send the right message.

Avoid using words that are too vague, generic, lengthy or misspelled. To create a succinct message, avoid using filler words or redundant messaging. Additionally, avoid improper punctuation, excessive punctuation, text in all caps or including too many special characters or emojis. Emojis can be extremely successful, but just like the words and tone used in your email, it all depends on your audience.

"When thinking about what to avoid including in a subject line, it truly depends based on the industry your email is targeting," said Sargeant. "For example, many industries find the occasional emoji in a subject line fun, but an IT audience hates emojis in subject lines, and it might be just enough for them to unsubscribe from your emails."  

Email subject line examples

The text of your subject line depends on your target audience and desired messaging. Creating great subject lines is an ongoing process and should be seen as an opportunity to connect with your audience.

To give you an idea of what a good email subject line looks like, Hampton and Sargeant listed the following examples: 

  • Today only: 25% off glass prints
  • Final days to save 15%
  • Make boredom a thing of the past
  • Who's ready for some good news?
  • Pringles + Baconator + Open the email
  • Your cat wants you to read this (from a veterinarian to pet owners)
  • The vibrant, empowering art of Lo Harris
  • New July books by authors you have read
  • Learn iPhone (iPhone emoji here) tips and tricks
  • Dad is sure to love this (heart emoji)
  • (Book emoji) Action required: Boston Public Library digital hold available to borrow

For more examples, check out this list by OptinMonster. Read sample subject lines categorized by target goals like fear, curiosity, humor, vanity, greed, sloth, pain points, retargeting and personalization.

Image Credit: BongkarnThankyakij / Getty Images
Skye Schooley
Skye Schooley Staff
Skye Schooley is a staff writer at and Business News Daily, where she has written more than 200 articles on B2B-focused topics including human resources operations, management leadership, and business technology. In addition to researching and analyzing products that help business owners launch and grow their business, Skye writes on topics aimed at building better professional culture, like protecting employee privacy, managing human capital, improving communication, and fostering workplace diversity and culture.