How to write high-performing email subject lines

Are you wondering how to write high-performing email subject lines?

Well, the role of email subject lines has evolved over the last 10 years. Often used to give context into what is inside the email, it has sometimes been abused with the likes of using RE: or FW: to sometimes trick the subscriber into an engagement.

We have seen the introduction of emojis, the pervasive use of “oops” and the subsequent messaging of “thought leaders” that they don’t carry much weight on opens any longer due to MPP

We will talk about why email subject lines still matter and introduce a method of writing them in the modern era.

In 2022, Email Subject Lines Still Matter…

In the post 9 Email Marketing Trends For 2022, I pointed to a trend around three-word subject lines, and while I still stand behind that trend, some of you might be thinking that it’s not sustainable. That said, email subject lines are still an essential part of the success of your email program but sometimes are the last thing on the checklist right before the email is sent. 

In the never-ending battle for inbox attention, those brands that can accentuate their brand identity and voice in the subject line give themselves a more significant opportunity for engagement in the inbox.

Historically, email subject lines have been tied to increasing open rates. While some of that still rings true, I believe there is a tremendous amount of value to testing tone, urgency, empathy, curiosity, icons, emojis, and more to “help” give your email a greater chance at subscriber engagement. 

Many industry professionals have their opinions on how to write subject lines, while some have A.I. write it for them. Please know that there is no right or wrong method, the only one you want to adopt and learn from.

At iPost, we love the D.I.C.E method to write the best email subject lines, which combines learnings from over 100+ combined years of email marketing experience and thousands and thousands of email subject lines written.

Writing Email Subject Lines Using D.I.C.E. Method

Just like there are many methods when it comes to testing in email, there are also many methods when it comes to writing email subject lines.

The D.I.C.E method works best when testing against each element, especially if the content being sent is for a unique audience. You will want to test this methodology against your existing way of writing subject lines. You should have a plan when using this method and each element should not be so repetitive when sending out email campaigns. 

The best industries for the D.I.C.E. method are

  • Casino
  • Franchise
  • Publishing
  • Restaurant
  • Association
  • Specialty Retail Organizations. 

D.I.C.E. Method Explained

The D.I.C.E. method of writing an email subject line consists of four elements:

  1. Desire
  2. Importance
  3. CTA (Call to Action)
  4. Empathy

The DICE Method Explained

We will break down each of these elements shortly, but you should know that there are no requirements for having two or more elements for each subject line that you write. 

However, if you choose only to use one element, ensure that you take that element and expose it in the copy of the SL. We recommend that you test around 60% of the time using conversions or clicks as the KPI while using one or a combination of these elements to see the winner. 

The elements of the D.I.C.E. Method and Examples


Most people want to feel needed and are naturally curious about things. To create desire, marketers must use words that evoke emotional curiosity from the desired CTA in the email.  For example:

B2B Example:

Original Subject Line 1: Whitepaper: How to gain greater efficiencies in your business

Subject Line 2 – D.I.C.E. enhanced: Be more effective RIGHT now.


Any Brand

Original Subject Line 1: Welcome to our newsletter!

Subject Line 2 – D.I.C.E. enhanced: Peek inside for your special….

When you use the desired element, be sure not to create a false sense of curiosity or use it as a deception just for the sake of false engagement. Use the goal of the email (buy/play/download etc.) as that hook to create desire.


Each person has a different idea and definition of important and valuable to them.  In a subject line, importance gives way to relevance, and relevancy is one of the main levers to engagement.

Importance is not always about creating a sense of urgency but finding that sweet spot of meaningful, purposeful, and persuasive words to garner action. Let’s take a look at some email subject line examples:


Original Subject Line 1: Hurry! Our sale ends soon.

Subject Line 2 – D.I.C.E. enhanced: Time is running out

Subject Line 3 – D.I.C.E. enhanced (with desire and importance): That is almost gone



Original Subject Line 1: It’s time to travel again.

Subject Line 2 – D.I.C.E. enhanced (with desire and importance): Feel the warmth now

Subject Line 3 – D.I.C.E. enhanced: Cocktails at 4? Sure.

Importance is hard to nail so it might be best used on specific segments. (e.g., the warmth subject line above being sent to folks in cold weather for traveling to a warmer destination) A desired email best practice would be to use importance and desire to create a more connected or relevant response.

CTA aka Call To Action

As marketers, we tend to think that our subscribers should know what to do or actions to take.  Unfortunately, that is not the case because people need to be led these days. 

Subscribers are busy and dealing with many things at once, so if the SL is not clear on the action to take, it might be pushed off and forgotten.  This CTA element is best used and tested in the following verticals: B2B, Franchise, and Associations. Let’s break this down:


Original Subject Line 1: Member Conference – April 3rd – 5th.

Subject Line 2 – D.I.C.E. enhanced: Sign up to attend XX conference.

Subject Line 3 – D.I.C.E. enhanced (with importance): Five days left to sign up to attend…..



Original Subject Line 1: Call with XYZ Franchise.

Subject Line 2 – D.I.C.E. enhanced: Open this: We have been trying to reach you regarding your..

Subject Line 3 – D.I.C.E. enhanced (with importance): Click inside this email.

Using CTA’s in email subject lines may seem a bit of a “doh” moment and somewhat simplistic, but you would be surprised as to how many brands assume many things in their email program.

It’s best to think about the basics and at least test to see if subject lines with CTA’s outperform in terms of conversions vs. those without.


The world continues to evolve due to the pandemic, but one crucial area is the ability for companies to exhibit more empathy in how they interact. While empathy should not be considered a trend, it is in the best interest of brands today to speak with instead of “to” their subscribers, and a great place to start is in the subject line.

Empathy should be inherent for every vertical.

Here are a few examples:


Original Subject Line 1: New Year. New slots. New chances to win.

Subject Line 2 – D.I.C.E. enhanced: Meet Sara, our newest slot manager.

Subject Line 3 – D.I.C.E. enhanced: Let’s win together.



Original Subject Line 1: Update your preferences.

Subject Line 2 – D.I.C.E. enhanced: Customize the way we communicate with you.

Subject Line 3 – D.I.C.E. enhanced: Tell us more about yourself.

The end goal of using empathy in subject lines is to not seem robotic or “marketing’ish” in the way you communicate with your subscribers. People appreciate real authenticity, interactions and want new ways to connect with brands. 

Final Thoughts

D.I.C.E  is not strict, hard to manage, nor should it be the mantra going forward in EVERY single subject line you do, but it should serve as a guidepost if you are hung up on creating subject lines. A suggestion would be to test the D.I.C.E method against your current methodology to see if in fact there is a lift across your email engagement KPI’s.

If you don’t have a methodology or a test plan, then it might be time to create a subject line play/test book.

Subject lines should not be the last thing you do when it comes to sending out an email campaign. They have to be carefully planned and tested against as the competition for inbox attention is getting more and more competitive.